In this paper, sparse activated subcarriers OFDM index modulation (SAS-OFDM-IM) and interpolated sparse activated subcarriers OFDM index modulation (ISAS-OFDM-IM) are proposed to improve the spectrum efficiency of OFDM modulation technique in visible light communication (VLC) systems. To be suitable for intensity modulation (IMod) by Light Emitting Diode (LED) used in VLC systems, the Unipolar Orthogonal Frequency Division Multiplexing (U-OFDM) is used. U-OFDM is more power efficient in an Additive White Gaussian Noise (AWGN) channel, which is prevalent in an optical wireless system. At the receiver, threshold detector has been used for detecting the activated subcarriers by taking the highest K out of N, where N is the total number of OFDM subcarriers and K is the total number of activated subcarriers. Results indicate that, using the proposed schemes can improve both the spectral efficiency …

Cognitive Radio Networks have been proposed as a promising solution for the spectrum deficiency problem. Even though, because of the opportunistic access and heterogeneity nature of these networks, they are exposed to threats such as the presence of jammer which aims to jeopardize the network transmissions. In this article, we introduce an anti-jamming cooperative framework to mitigate or minimize the impact of the jammer on the cognitive radio network. In the proposed solution, the secondary coordinator distributes the Secondary Users (SU) over the selected channel and pairs the SUs to form cooperative coalitions which utilize cooperative transmission to establish more robust transmission links to overcome the effect of the jammer power. Stackelberg game is used to model the interaction between the jammer and the network coordinator. The outcomes show the superiority of using cooperative transmission over the traditional direct transmission. Also, the performance of the secondary network enhances as the number of SUs increases due to the higher probability of forming cooperative groups. © Springer Nature Switzerland AG 2020.

Limitations of using the radio spectrum have risen because of the increasing demand for wireless communication services. However, as a large portion of the Primary User’s (PU) spectrum is not effectively utilized because of assignment a fixed spectrum; the Cognitive Radio (CR) approach is considered as a solution, which enables the best access to the available spectrum. Spectrum sensing detects the temporarily unused frequency bands across the PU radio spectrum. In this paper, a novel approach for improving the spectrum sensing in the cognitive radio network is proposed for a network consists of a Primary User (PU), Secondary Users (SUs), and single Fusion Center (FC). The proposed approach is achieved by forming a centralized cooperation sensing among cognitive radio users in the noisy environment. All SUs use the energy detection as a sensing technique, and then the result will be sent to FC to …

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In the study, the effect of nano ferric oxide (Fe2O3) modification was investigated to improve the rheological properties of bitumen and mechanical properties of Hot Mix Asphalt (HMA). Rutting potential and non-recoverable compliance (Jnr) were determined after subjecting modified bitumen to short-term and long-term aging. Multiple Stress Creep Recovery (MSCR) test was conducted to evaluate Jnr of bitumen and performance grade. Low temperature stiffness and flexural properties of modified bitumen were also determined. Indirect Tensile Strength (ITS) and Tensile Strength Ratio (TSR) of HMA modified with nano Fe2O3 was determined. Rutting was also determined by Hamburg Wheel Tracking Device (HWTD) for HMA modified with nano Fe2O3. Solar reflection was measured on HMA modified with nano Fe2O3. Results showed that, the nano Fe2O3 improved the rutting potential and non-recoverable compliance. Maximum rutting performance was observed by 5% Fe2O3 modified bitumen. The non-recoverable compliance and the rutting resistance have related. Modified HMA samples have higher strength value than reference sample. Nano Fe2O3 modification of HMA was provided resistance against moisture damage. 1% Fe2O3 modified HMA has the highest rutting resistance with the maximum 6 mm rut depth. Heat islands were increased by nano Fe2O3 modification.

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Built heritage forms a unique asset by expressing the richness and diversity of our history, possessing vast amounts of information that varies from factual and explicit, to more tacit and embedded. Tacit knowledge of built heritage is typically more challenging to communicate to visitors in understandable and engaging ways due to its implicit and abstract character. Therefore, we investigate how built heritage information can be disclosed via simultaneous and integrated physical and digital means, and how this information can be communicated to visitors in more engaging, educational and meaningful ways. In this thesis we present the approach of "Phygital Heritage", which entails how heritage information can be disclosed via simultaneous and integrated physical and digital means. We hypothesize that this approach forms a potential medium for more engaging and meaningful communication of heritage information to a broader public. It even enables heritage visitors to appreciate heritage in more experiential ways, and to raise community awareness about heritage assets. Through a set of in-the-wild studies, in which interactive phygital prototypes were designed and deployed in real-world heritage and museum environments, we explore how the seamless integration of digital technology into physical reality facilitates the communication of built heritage information to museum visitors and how it affects user engagement. In Saqqara Entrance Colonnade, through a between-group comparative study in a real-world museum context, we examined how the tangible characteristics of an interactive museum prototype influence how visitors understand tacit knowledge of built heritage; In Nimrud Relief, through a field study in a real-world museum environment, we investigated how an augmented reality experience impacts the architectural contextualization of an isolated artifact from the Nimrud palace in Iraq; In Graethem Chapel, through an in-the-wild study, we investigated how an in-situ interactive projection mapping enables the communication of the spatiotemporal transformation of a medieval chapel that occurred during the last 850 years; and In Neferirtenef Tomb-Chapel, through a field study in a real-world museum environment, we investigated how a tangible gamification installation supports informal cultural learning of young museum visitors and how it encourages collaboration among them. In summary, this thesis contributes to the knowledge about the communication of built heritage information by demonstrating how this information can be disclosed via simultaneous and integrated physical and digital means, enabling the broader public to appreciate heritage in more experiential ways.

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