1,720,973 research outputs found
Conceptual exploration for airborne wind energy system for electricity generation in Pulau Perhentian Kecil, Malaysia – MBSE approach
No full textRenewable energy plant research such as wind energy has been on the rise for the past few decades. The objective of this paper is to do a conceptual exploration of the new type of wind harvesting system known as Airborne Wind Energy System (AWES) to be used in Pulau
Perhentian Kecil using Model-Based Systems Engineering Approach (MBSE) where the final selection is chosen using TOPSIS method.
There are several types of concept designs to choose from based on their unique mode of operation. The candidate concept designs are
from Ampyx Power B.V, Magenn Power, Makani and Altaeros Energies. From the TOPSIS analysis, Ampyx Power B.V has been selected due to its highest fulfilment of the requirements. This exploration into several potential AWES may help solve the deficiency of the current systems and advantageously utilise the suitable geographical factors of Pulau Perhentian Kecil
Development of collision avoidance system for useful UAV applications using image sensors with laser transmitter
Get PDFThe main goal of this study is to demonstrate the approach of achieving collision avoidance on Quadrotor Unmanned Aerial Vehicle (QUAV) using image sensors with colour-based tracking method. A pair of high definition (HD) stereo cameras were chosen as the stereo vision sensor to obtain depth data from flat object surfaces. Laser transmitter was utilized to project high contrast tracking spot for depth calculation using common triangulation. Stereo vision algorithm was developed to acquire the distance from tracked point to QUAV and the control algorithm was designed to manipulate QUAV's response based on depth calculated. Attitude and position controller were designed using the non-linear model with the help of Optitrack motion tracking system. A number of collision avoidance flight tests were carried out to validate the performance of the stereo vision and control algorithm based on image sensors. In the results, the UAV was able to hover with fairly good accuracy in both static and dynamic collision avoidance for short range collision avoidance. Collision avoidance performance of the UAV was better with obstacle of dull surfaces in comparison to shiny surfaces. The minimum collision avoidance distance achievable was 0.4 m. The approach was suitable to be applied in short range collision avoidance
Relative position-based collision avoidance system for swarming UAVs using multi-sensor fusion
Get PDFThis paper presents the development of a quadrotor unmanned aerial vehicle (UAV) that is capable of quad-directional collision avoidance with obstacles in swarming applications through the implementation of relative position based cascaded PID position and velocity controllers. A collision avoidance algorithm that decides evasive manoeuvres in two dimensional flight by the means of net error calculation was developed. Sensor fusion of ultrasonic (US) and infrared (IR) sensors was performed to obtain a reliable relative position data of obstacles which is then fed into collision avoidance controller (CAC) for generating necessary response in terms of attitude commands. Flight tests performed proved the capability of UAV to avoid collisions with the obstacles and dummy non-flying UAVs that existed at a closer distance in its four primary directions of detections during flight successfully
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Computational analysis of the rotating cylinder embedment onto flat plate
No full textThe Magnus effect and its evolution have greatly affected the aerospace industry over the past century to date. Nevertheless, cylinder embedment onto a flat plate offers a new discovery that is yet to be investigated, specifically whether the concept could enhance the aerodynamic properties of the flat plate following the Magnus effect momentum injection. Over the past decade, the use of a rotating cylinder on an aerofoil has existed from past researches studies where the embedment has significantly increased in its aerodynamic performance better than the one without Magnus application. However, it would be hard to achieve experimental-wise as an accurate measurement and fabrication would be needed to have the same resulting effects. Here, most of the researchers would not focus deeply on the placement of the cylinder as this may increase their fabrication and testing complications. Therefore, the current study delineates the use of flat plate as the foundation design to encounter the arise matter by reducing its complication yet easy to manufacture experimentally. In this work, the model output was evaluated by using ANSYS WORKBENCH 2019 software to simulate two-dimensional flow analysis for the rotational velocities of 500 RPM and 1000 RPM, respectively. This was done for different Reynolds numbers ranging from 4.56E+05 to 2.74E+06 which implicitly implied with free stream velocities varying from 5 m/s to 30 m/s for different angles of attack between 0 to 20 degrees. Prior to developing the best model embedment, the mesh independency test was validated with an error of less than 1%. The study resulted in a remarkable trend that was noticeably up to 32% (500 RPM) and 76% (1000 RPM) better in compared to the one without momentum injection. Similarly, the high recovery led to a tremendously lower of 51% (500 RPM) and 99% (1000 RPM), respectively. In sum, these findings generated a stall angle delay of up to 26% (500 RPM) and 78% (1000 RPM) accordingly
Implementation of extended high-gain observer in low-cost optitrack motion tracking system for UAV control
Get PDFThe objective of this paper is to present the implementation procedure and experimental results of using Extended High-Gain Observer (EHGO) in estimating the states from low-cost Optitrack camera that is being used as the motion tracking in the Unmanned Aaerial Vehicle (UAV) system. Owing to the low-cost sensor, the signal produced is noisy which requires filters to produce a good signal. The standard procedure to obtain differentiated signal is complex. Therefore, this paper proposed an alternative method using EHGO. The theory of EHGO is presented, and the steps taken to transform EHGO algorithm from continuous to digital form are described. Validation is performed in open-loop and closed-loop flight test to analyze the performance. The results show that EHGO able to estimate the velocity state at the same performance quality as the standard procedure using Kalman filter. Nonetheless, the advantage of EHGO is due to its simple algorithm hence minimal parameters to tune
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Unmanned aerial vehicle assisted localization using multi-sensor fusion and ground vehicle approach
No full textAn accurate localization of unmanned aerial vehicles (UAVs) is crucial
for the execution of its growing applications such as surveillance and rescue
missions. Previous researches have extensively studied the usage of sensor
fusion algorithms to combine the sensors on board of the UAV to improve its
localization. However, application of collaborative localization techniques in
UAV navigation has not been investigated thus far. These novel algorithms
stand to improve the stability and accuracy of UAV localization approaches
through incorporation of additional sensors from other moving targets such
as an unmanned ground vehicle (UGV). It is believed that the accuracy of the
UAV localization will be further improved with help of multi-sensor Kalman
filter (MS-KF) and this collaborative sensor fusion approach leads to a better
accuracy than that of the single-sensor Kalman filter (SS-KF) approach. The
obtained results in this study show promising improvements of both position
and attitude with MS-KF. In comparison, the mean square error (MSE) for
position is 0.005 and 0.026 for the developed MS-KF and SS-KF, respectively.
Meanwhile, MSE for attitude is 2.396e-5 and 8.11e-4 for the developed MS-
KF and SS-KF, respectively. Based on these findings, the positive potential
of collaborative sensor fusion approach has been aptly highlighted
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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