21 research outputs found
Differentiation and Localization of Ground RF Transmitters Through RSSI Measures From a UAV
No full textLow-altitude Unmanned Aerial Vehicles (UAVs) are a valuable solution for data gathering, surveillance, warfare, and mapping. In these applications, differentiating and estimating the position of ground Radio Frequency (RF) emitters is pivotal. In order to achieve this, we define an experimental setup based on Received Signal Strength Indicator (RSSI) collected by a single UAV at different points of a predefined trajectory. The experimental setup is evaluated for the two unlicensed frequency bands of 2.4GHz and 865MHz with and without interference, respectively. We show that the application of the maximum likelihood algorithm to the RSSI measures collected in experiments conducted in rural areas gives a mean absolute localization error of about 5m and 4m for a single transmitter with and without interference, respectively. A threshold-based technique is proposed to improve the accuracy in the presence of interference. For multiple transmitters, the RSSI data are divided into clusters and fed into a localization algorithm. A k-means clustering algorithm eliminates user intervention and identifies the number of RF emitters in the area. As a further contribution of the paper, we performed a validation phase where the UAV flight path and data collection are simulated using the QuaDRiGa realistic radio impulse channel model
Experimental Jamming Detection Using Machine Learning in IEEE 802.11 Enterprise Networks
No full textExperimental UAV-Aided RSSI Localization of a Ground RF Emitter in 865 MHz and 2.4 GHz Bands
No full textUnmanned Aerial Vehicles (UAVs) can be used as low altitude platforms in several applications. In this paper, we propose their use to localize a ground Radio Frequency (RF) emitter by collecting measures of the Received Signal Strength Indicator (RSSI) at different positions. The main contribution of the work consists in the definition of an experimental setup for the simultaneous measures of RSSI and receiver position. The RSSI is measured by an actual transceiver, the Adalm Pluto Software Defined Radio (SDR) development board, programmed with the open-source software GNU Radio. The position is provided by GPS and Inertial Measuring Unit (IMU) sensors on the drone. The measures are acquired in the 865MHz Short Range Device (SRD) and 2.4 GHz Industrial Scientific Medical (ISM) unlicensed frequency bands. Since the ISM measures can be affected by interference generated by different sources (e.g. Wi-Fi access points and UAV controller), the SRD band is exploited for collecting the RSSI measures with less interference. A maximum likelihood (ML) algorithm is applied to the collected data for estimating the transmitter location. For the considered setup we show that the mean absolute localization error is around 4m without interference and 5m with interference. A threshold-based technique is proposed to improve the accuracy in presence of interference
Effect of hidden terminal node in DSRC and V2V communication
No full textLAUREA MAGISTRALELa tecnologia di comunicazione Vehicle-to-Everything (V2X) si prevede che migliorerà
la sicurezza stradale e aumenterà l’efficienza dei sistemi di trasporto. L’aumento dei
veicoli autonomi rappresenta una nuova tendenza in questo nuovo mondo, dove la comunicazione tra di loro sarà essenziale. Abbiamo cercato di evidenziare la differenza tra
la comunicazione Wi-Fi e la comunicazione dedicata a corto raggio (DSRC) per comprendere l’architettura di ciascuna di esse. Successivamente, miriamo ad esaminare vari
metodi che possono influenzare l’affidabilità dei sistemi di comunicazione, pertanto, in
questo contesto, introduciamo vari tipi di jamming che influenzano il rapporto di consegna
dei pacchetti (PDR). La diffusione di messaggi di sicurezza richiede un’alta affidabilità
e un’interazione istantanea tra i veicoli, anche in condizioni difficili. Nel nostro
studio, identifichiamo inizialmente il problema predominante comunemente riscontrato
nelle Comunicazioni a Corto Raggio Dedicato (DSRC), che porta a una riduzione notevole
del PDR, identificato come il problema del terminale nascosto. Introduciamo questo
concetto e chiarifichiamo sia la sua meccanica operativa sia il suo potenziale impatto sul
PDR. Formuliamo un’espressione analitica per il PDR, sottolineando il problema del terminale nascosto come un contributo chiave alla degradazione delle prestazioni. Inoltre,
esploriamo come le varie velocità di trasmissione dei dati influenzano il PDR. I nostri
risultati di simulazione dimostrano una marcata diminuzione del PDR in situazioni compromesse da problemi di terminali nascosti.Vehicle-to-Everything (V2X) communication technology is anticipated to enhance road
safety and increase the efficiency of transportation systems. The increased of autonomous
vehicles is new a trend in this new world, where the communication between them will be
essential. We tried to highlight the difference between Wi-Fi communication and dedicated
short range communication (DSRC) to understand the architecture of each of them.
Subsequently, we aim to examine various methods that can influence the reliability of communication systems, hence in this context, we introduce various types of jamming that
affect the packet delivery ratio (PDR). The dissemination of safety messages requires high
reliability and instantaneous interaction between vehicles, even under difficult conditions.
In our study, we initially identify the predominant issue commonly encountered in DSRC,
leading to a noticeable reduction in the PDR, identified as the hidden terminal problem,
We introduce this concept and elucidate both its operational mechanics and its potential
impact on the PDR. We formulate an analytical expression for the PDR, emphasizing the
hidden terminal problem as a key contributor to performance degradation. Furthermore,
we explore how varying data rates affect the PDR. Our simulation results demonstrate a
marked decrease in PDR in situations compromised by hidden terminal challenges
Strain analysis in glenohumeral capsule through finite element modelling
No full textThe injury mechanics and strain distribution in the glenohumeral capsule at a particular joint angle have been studied extensively. However, there is a lack of information on the strain distributions in the capsule under complex joint angles, i.e, during the activities of daily living (ADL). To investigate the mechanical response of the capsule under the kinematics of the forward reach, a subject specific finite element model of the glenohumeral joint with the capsule was developed. Since the mechanical properties of the capsule under multiaxial loading were unknown we proposed an inverse finite elements based optimization routine to determine the material coefficients of the capsule. Several constitutive material models were evaluated to identify feasibility of convergence for the complex loading associated with physiological tasks. We established limits for the material coefficients of the Mooney-Rivlin model used to model the capsule. The Mooney-Rivlin model with the material coefficients C1 = 6, C10 = 6.5, and D1 = 0.12 converged for around 50% of the cycle. The results also suggest that the peak strain occurred on the inferior aspect of both the anterior and posterior side of the capsule. This work serves as the basis for future comparisons of material models and can be extended to other activities of daily living.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01The student, Vineeth Bodapati, accepted the attached license on 2019-07-18 at 20:31.The student, Vineeth Bodapati, submitted this Thesis for approval on 2019-07-18 at 20:40.This Thesis was approved for publication on 2019-07-19 at 11:25.DSpace SAF Submission Ingestion Package generated from Vireo submission #14386 on 2019-11-26 at 13:06:21Made available in DSpace on 2019-11-26T20:49:34Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-07-19Embargo set by: Seth Robbins for item 112986
Lift date: 2021-11-26T20:49:41Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 112986 on 2021-11-27T10:15:30Z
Computational Modelling of the Oryon Watermill: A Nested Fluid-Structure Interaction Problem with Non-Smooth Dynamics
No full textThe current research aims to numerically predict the performance characteristics of the Oryon Water Mill. The simulation mechanism to be developed, begins at the structural solver part of a partitioned FSI solver, upon which the unique functional characteristics of the turbine are embedded. The modelling is carried out to account for the turbine’s functional characteristics like, multiple nested rigid body FSI dynamics, non-smooth dynamics and lamella partial torque contributions. The solver is built to resolve the turbine dynamics in two dimensions and re-scale the final result with respect to the turbine core height. The results of the simulation show the predicted torque to be of similar trend as that of the experimental data collected by MARIN, while being an over-prediction by a factor of two. The optimal performance range of the turbine is predicted within an error bound of 0.1RPS. The overprediction of the torque is considered to be a result of the 2D solution not accounting for the flow leakage in the third and unaccounted for direction. The time variant fluid solution is found to be unstable due to the spikes observed in the torque time signal and is a consequence of the perfect momentum sink assumption employed in the modelling of the lamella’s non-smooth dynamics. The lamella dynamics are observed to not convergence to fully periodic behaviour and the sensitivity of the lamella’s dynamics is considered to be the root cause. The velocity Verlet based structural solver does not provide fluid-structure coupling iterations, the inclusion of which, could improve the stability of the fluid solution.This endeavour establishes a foundation for the predictive numerical simulation of the OWM in the form of baseline numerical simulation results and a developed simulation framework
Who Manages What? Covid-19 and the Centre-State Division of Responsibilities in Indian Democracy
No full textThe Constitution of India has provisions of separation of power in order to facilitate the smooth functioning of the federal structure consisting of the central and state governments. Accordingly, a list has been illustrated in the Constitution of India where the Centre and State governments will have autonomous or shared ownership and responsibilities. As per this list, the subject of health comes under the purview of the state government. In this article, the author explores various aspects associated with the COVID-19 pandemic that has necessitated the central government to step into the domain of health, which is a state subject
Differentiation and Localization of Ground RF Transmitters Through RSSI Measures from a UAV
No full textThis paper explores the experimental localization of single and multiple ground RF transmitters using both traditional localization and machine learning algorithms. For the localization of a single transmitter, the setup is evaluated in two unlicensed frequency bands with and without interference. A threshold approach is proposed to improve accuracy in the presence of interference. To localize multiple transmitters, the RSSI data are divided into clusters by a k-means clustering algorithm and fed into a localization algorithm. These experimental results are preceded by an analysis phase where the UAV flight path and data collection are simulated using the QuaDRiGa channel model.</p
Beyond Empire: Postcolonialism and Mission in a Global Context, By Jonathan Ingleby. Milton Keynes, UK, Author House 2010. Pp. xix + 279. £13.50.
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