4,513 research outputs found

    Thermal and solutal stratification on MHD nanofluid flow over a porous vertical plate

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    Nanoparticles have the highest credibility to develop the thermal properties compared to conventional particle fluid suspension. Thermal and solutal stratification on heat and mass transfer induced due to a nanofluid over a porous vertical plate is analyzed. The transport equations engaged in the study include the effect of Brownian motion and thermophoresis particle deposition. The nonlinear governing equations and their related boundary conditions are initially looked into dimensionless forms by similarity variables. The resulting equations are solved numerically utilizing the fourth-fifth order Runge–Kutta–Fehlberg method with shooting technique (MAPLE 18). It is investigated that the temperature of the nanofluid and the concentration fraction decelerate with increase in thermal and solutal stratificatio

    A unified approach to cooperative and non-cooperative sense-and-avoid

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    Cooperative and non-cooperative Sense-and-Avoid (SAA) capabilities are key enablers for Unmanned Aircraft Vehicle (UAV) to safely and routinely access all classes of airspace. In this paper state-of-the-art cooperative and non-cooperative SAA sensor/system technologies for small-to-medium size UAV are identified and the associated multi-sensor data fusion techniques are introduced. A reference SAA system architecture is presented based on Boolean Decision Logics (BDL) for selecting and sorting non-cooperative and cooperative sensors/systems including both passive and active Forward Looking Sensors (FLS), Traffic Collision Avoidance System (TCAS) and Automatic Dependent Surveillance - Broadcast (ADS-B). After elaborating the SAA system processes, the key mathematical models associated with both non-cooperative and cooperative SAA functions are presented. The analytical models adopted to compute the overall uncertainty volume in the airspace surrounding an intruder are described. Based on these mathematical models, the SAA Unified Method (SUM) for cooperative and non-cooperative SAA is presented. In this unified approach, navigation and tracking errors affecting the measurements are considered and translated to unified range and bearing uncertainty descriptors, which apply both to cooperative and non-cooperative scenarios. Simulation case studies are carried out to evaluate the performance of the proposed SAA approach on a representative host platform (AEROSONDE UAV) and various intruder platforms. Results corroborate the validity of the proposed approach and demonstrate the impact of SUM towards providing a cohesive logical framework for the development of an airworthy SAA capability, which provides a pathway for manned/unmanned aircraft coexistence in all classes of airspace

    Some characteristics of the larval breeding sites of Anopheles culicifacies species B and E in Sri Lanka

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    Background & objectives : Anopheles culicifacies Giles, the major malaria vector in Sri Lanka, existsas a species complex comprising two sympatric sibling species— species B and E. Species E is reportedto be the major vector of Plasmodium vivax and P. falciparum parasites in Sri Lanka, whilst speciesB is a poor or nonvector as in India. Knowledge of the breeding habits of the two sibling species canhelp in designing optimal vector control strategies. Hence, a survey was conducted in Sri Lanka tostudy the preferential breeding habitats of An. culicifacies species B and E.Methods: Immature forms of An. culicifacies were collected from identified breeding sites in malariousdistricts. Collected larvae were typed for their sibling species status based on mitotic Y-chromosomestructure. Data was analysed using Statistical Package for Social Science version 10.0.Results: An. culicifacies immature forms were found in 23 collection sites. Among these samples19 were found to have species E and four to have species B. All species B larvae were collected fromTonigala village in the Puttalam district. None of the 23 sites was found to have both species B and E.Species E, the major vector of malaria, appears to breed in variety of breeding sites which can be of anindication of its adaptive variation to exploit breeding sites with varying limnological characteristics.Interpretation & conclusion: The present findings have to be taken into account when formulatingmore effective larval control measures. They also show the need for a detailed study of possibledifferent preferences for larval breeding sites between species B and E

    Communication, navigation and surveillance performance criteria for safety-critical avionics and ATM systems

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    The demand for improved safety, integrity and efficiency due to the rapid growth of aviation sector and the growing concern for environmental sustainability issues poses significant challenges on the development of future Communication, Navigation and Surveillance/Air Traffic Management (CNS/ATM) and Avionics (CNS+A) systems. High-integrity, high-reliability and all-weather services are required in the context of four dimensional Trajectory Based Operations / Intent Based Operations (TBO/IBO). The Next Generation Flight Management Systems (NG-FMS) and the Next Generation Air Traffic Management (NG-ATM) systems are developed allowing automated negotiation and validation of the aircraft intents provided by the NG-FMS. After describing the key system architectures, the mathematical models for trajectory generation and CNS performance criteria evaluation are presented. In this paper, the method for evaluating navigation performance is presented, including a detailed Monte Carlo simulation case study. The proposed approach will form a basis for evaluating communication and surveillance performances as well in future research. The Monte Carlo simulation results demonstrate the capability of the proposed CNS+A system architectures to comply with the required navigation performance criteria in the generation of optimized aircraft trajectory profiles

    PREDICTIVE TIME MODEL OF AN ANGLIA AUTOFLOW MECHANICAL CHICKEN CATCHING SYSTEM

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    In this project, a predictive time model was developed for an Anglia Autoflow mechanical chicken catching system. At the completion of poultry growout, hand labor is currently used to collect the birds from the house, although some integrators are beginning to incorporate mechanical catching equipment. Several regression models were investigated with the objective of predicting the time taken to catch the chicken. A regression model relating distance to total time (sum of packing time, catching time, movement to catching and movement to packing) provided the best performance. The model was based on data collected from poultry farms on the Delmarva Peninsula during a six-month period. Statistical Analysis System (SAS) and NeuroShell Easy Predictor were used to build the regression and neural network models respectively. Model adequacy was established by both visual inspection and statistical techniques. The models were validated with experimental results not incorporated into the initial model.Livestock Production/Industries,

    Bistatic LIDAR system for the characterisation of aviation-related pollutant column densities

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    In this paper we investigate an innovative application of Light Detection and Ranging (LIDAR) technology for aviation-related pollutant measurements. The proposed measurement technique is conceived for the high-resolution characterisation in space and time domains of aviation-related pollutant gases. The system performs Integral Path Differential Absorption (IPDA) measurement in a bistatic LIDAR measurement setup. The airborne component consists of a tuneable Near Infrared (NIR) laser emitter installed on an Unmanned Aircraft (UA) and the ground sub-system is composed by a target reference surface (calibrated for reflectance) and a differential transmittance measuring device based on a NIR Camera calibrated for radiance. The specific system implementation for Carbon Dioxide (CO2) measurement is discussed. A preliminary assessment of the error figures associated with the proposed system layout is performed

    4-dimensional trajectory generation algorithms for RPAS mission management systems

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    This paper presents the algorithms enabling real-time 4-Dimensional Flight Trajectory (4DT) functionalities in Next Generation Mission Management Systems (NG-MMS), which are the core element of future Remotely Piloted Aircraft Systems (RPAS) avionics. In particular, the algorithms are employed for multi-objective optimisation of 4DT intents in various operational scenarios spanning from online strategic to tactical and emergency tasks. The adopted formulation of the multi-objective 4DT optimisation problem includes a number of environmental objectives and operational constraints. In particular, this paper describes the algorithm for planning of 4DT based on a multi-objective optimisation approach and the generalised expression of the cost function adopted for penalties associated with specific airspace volumes, accounting for weather, condensation trails and noise models

    Multi-objective optimisation of aircraft flight trajectories in the ATM and avionics context

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    The continuous increase of air transport demand worldwide and the push for a more economically viable and environmentally sustainable aviation are driving significant evolutions of aircraft, airspace and airport systems design and operations. Although extensive research has been performed on the optimisation of aircraft trajectories and very efficient algorithms were widely adopted for the optimisation of vertical flight profiles, it is only in the last few years that higher levels of automation were proposed for integrated flight planning and re-routing functionalities of innovative Communication Navigation and Surveillance/Air Traffic Management (CNS/ATM) and Avionics (CNS+A) systems. In this context, the implementation of additional environmental targets and of multiple operational constraints introduces the need to efficiently deal with multiple objectives as part of the trajectory optimisation algorithm. This article provides a comprehensive review of Multi-Objective Trajectory Optimisation (MOTO) techniques for transport aircraft flight operations, with a special focus on the recent advances introduced in the CNS+A research context. In the first section, a brief introduction is given, together with an overview of the main international research initiatives where this topic has been studied, and the problem statement is provided. The second section introduces the mathematical formulation and the third section reviews the numerical solution techniques, including discretisation and optimisation methods for the specific problem formulated. The fourth section summarises the strategies to articulate the preferences and to select optimal trajectories when multiple conflicting objectives are introduced. The fifth section introduces a number of models defining the optimality criteria and constraints typically adopted in MOTO studies, including fuel consumption, air pollutant and noise emissions, operational costs, condensation trails, airspace and airport operations

    Identification of Continuing Professional Development Needs of Primary School English Teachers of Kuala Terenganu District

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    The study was carried out mainly to identify the perceived needs for continuing professional development of primary school English teachers of Kuala Terengganu District. It also sought to find out the relationship between selected variables and the perceived needs for continuing professional development. The data was collected using a questionnaire from 82 primary school English teachers of Kuala Terengganu district. The findings of the study indicated that majority of the respondents have high perceived needs for continuing professional development. The study also revealed that the respondents have perceived needs in all the six categories identified in the questionnaire which were (A) Knowledge, (B) Teaching Strategies, (C) Classroom-Based Skills, (D) Pastoral Care, (E) Student Management Skills and (F) Personal Development. It was found that there was a significant correlation between age and perceived needs for continuing professional development but it was low in nature. The study recommended that provision of professional development activities for primary school English teachers of Kuala Terengganu District should be based on a needs assessment and teachers should be allowed to choose in-service courses based on their own needs. The study has also suggested that further research should be conducted to obtain a more in-depth view of the perception of professional needs of English teachers through other research designs

    Avionics sensor fusion for small size unmanned aircraft Sense-and-Avoid

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    Cooperative and non-cooperative Sense-and-Avoid (SAA) systems are key enablers for Unmanned Aircraft (UA) to routinely access non-segregated airspace. In this paper some state-of-the-art cooperative and non-cooperative sensor and system technologies are investigated for small size UA applications, and the associated multisensor data fusion techniques are discussed. Non-cooperative sensors including both passive and active Forward Looking Sensors (FLS) and cooperative systems including Traffic Collision Avoidance System (TCAS), Automatic Dependent Surveillance - Broadcast (ADS-B) system and/or Mode C transponders are part of the proposed SAA architecture. After introducing the SAA system processes, the key mathematical models for data fusion are presented. The Interacting Multiple Model (IMM) algorithm is used to estimate the state vector of the intruders and this is propagated to predict the future trajectories using a probabilistic model. Adopting these mathematical models, conflict detection and resolution strategies for both cooperative and un-cooperative intruders are identified. Additionally, a detailed error analysis is performed to determine the overall uncertainty volume in the airspace surrounding the intruder tracks. This is accomplished by considering both the navigation and the tracking errors affecting the measurements and translating them to unified range and bearing uncertainty descriptors, which apply both to cooperative and non-cooperative scenarios. Detailed simulation case studies are carried out to evaluate the performance of the proposed SAA approach on a representative host platform (AEROSONDE UA) and various intruder platforms, including large transport aircraft and other UA. Results show that the required safe separation distance is always maintained when the SAA process is performed from ranges in excess of 500 metres
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