Two-hop cognitive DF relaying with wireless power transfer in time and power domains

In this paper, we consider a wireless powered cognitive relaying system with a secondary relay (SR) capable of harvesting wireless energy. Along with an access point (AP) continuously transmitting the primary data to a primary user (PU), a secondary source (SS) can transmit the secondary data to a secondary destination (SD) with the help of SR using the decode-and-forward (DF) protocol. SR can harvest energy from both SS and AP in both time and power domains using time-splitting and power-splitting techniques. The interference from primary data transmissions can help boost the amount of harvested energy at SR. The transmit power of SS is regulated by the interference threshold at PU and the allowable peak power. Despite the above two constraints, the transmit power of SR is further constrained by the amount of harvested energy. Once SR successfully decodes the data from SS, it will forward the data to SD using a constrained power. We analyze the approximate outage probabilities for both primary and secondary systems. Simulation results are provided to verify the effectiveness of our theoretical analysis and reveal the impacts of various parameters to the outage performance.

Christian Metz

The film theory of Christian Metz (b. 1931–d. 1993) forms part of the structuralist revolution of ideas that challenged the phenomenology prevalent in France in the 1950s. Metz developed a structuralist (or its derivative, semiological) theory of film in the 1960s and inaugurated a groundbreaking theory and method of analysis that transformed film into a semiological object, in which film’s specificity was no longer perceived in terms of surface sensory properties or a conscious aesthetic experience. Instead, Metz reconceived filmic specificity, this most sensory of objects, as a type of signification—as the manifestation of a more fundamental, nonobservable, underlying finite abstract system of codes. To conceive film as signification involves a shift in perspective, from the study of film as a consciously experienced, continuous sensory object to the study of the abstract underlying system of discrete (or discontinuous) codes that generates and organizes those experiences. In terms of the history of ideas, semiology parallels the epistemology of philosophers such as Immanuel Kant, who argued that an underlying transcendental system of conceptual categories in the mind structures and makes possible human experience. Semiology’s innovation was to replace this underlying transcendental system with a historically and culturally contingent system of underlying codes. In the 1970s Metz addressed the limitations of structuralism and semiology by adopting a post-structuralist framework premised on theories of enunciation, Lacanian psychoanalysis, and phenomenology. For Metz, enunciation (which emphasizes signs of the speaker and receiver in a text) and psychoanalysis (which emphasizes traces of the unconscious in a text) enabled him to rethink his study of codes as secondary systems of signification, which are underpinned and driven by more-fundamental primary processes of signification (unconscious drives, fantasy, and dream logic). In his final work in the early 1990s, Metz developed a theory of filmic enunciation focused on the impersonal traces of a film’s production; that is, enunciative markers that are reflexive, that refer back only to the film itself.

Optimal Performance Comparison of Nonlinear Energy Sinks and Linear Tuned Mass Dampers

This paper studies a targeted energy transfer (TET) mechanism for a two-degree-of-freedom (TDOF) model in free vibration. The model comprises a primary linear system and a secondary system in the form of an energy sink which can be nonlinear. The free vibrations are considered subject to an impulsive excitation exerted on the primary system, leading to a nonzero initial velocity. The goal is to obtain the spring parameters in the nonlinear energy sink (NES) so as to maximize an energy dissipation measure (EDM) representing the percentage of impulsive energy that is absorbed and dissipated in the NES. A global optimization algorithm is used for this purpose. The optimal performance is assessed for the purely linear, linear-cubic, and purely cubic configurations of the spring connecting the primary and secondary systems. The corresponding results are compared with each other. The optimization process is performed for the EDM averaged over given ranges of the initial impulse and natural frequency in the primary system. It is shown that the type of the optimal configuration can vary depending on these ranges.

Performance Analysis and Optimization of a Cooperative Transmission Protocol in NOMA-Assisted Cognitive Radio Networks with Discrete Energy Harvesting

In this paper, we propose a spectrum-sharing protocol for a cooperative cognitive radio network based on non-orthogonal multiple access technology, where the base station (BS) transmits the superimposed signal to the primary user and secondary user with/without the assistance of a relay station (RS) by adopting the decode-and-forward technique. RS performs discrete-time energy harvesting for opportunistically cooperative transmission. If the RS harvests sufficient energy, the system performs cooperative transmission; otherwise, the system performs direct transmission. Moreover, the outage probabilities and outage capacities of both primary and secondary systems are analyzed, and the corresponding closed-form expressions are derived. In addition, one optimization problem is formulated, where our objective is to maximize the energy efficiency of the secondary system while ensuring that of the primary system exceeds or equals a threshold value. A joint optimization algorithm of power allocation at BS and RS is considered to solve the optimization problem and to realize a mutual improvement in the performance of energy efficiency for both the primary and secondary systems. The simulation results demonstrate the validity of the analysis results and prove that the proposed transmission scheme has a higher energy efficiency than the direct transmission scheme and the transmission scheme with simultaneous wireless information and power transfer technology.