Joint Spectrum Sensing and Resource Allocation for OFDM-based Transmission with a Cognitive Relay

In this paper, we investigate the joint spectrum sensing and resource allocation problem to maximize throughput capacity of an OFDM-based cognitive radio link with a cognitive relay. By applying a cognitive relay that uses decode and forward (D&F), we achieve more reliable communications, generating less interference (by needing less transmit power) and more diversity gain. In order to account for imperfections in spectrum sensing, the proposed schemes jointly modify energy detector thresholds and allocates transmit powers to all cognitive radio (CR) subcarriers, while simultaneously assigning subcarrier pairs for secondary users (SU) and the cognitive relay. This problem is cast as a constrained optimization problem with constraints on (1) interference introduced by the SU and the cognitive relay to the PUs; (2) miss-detection and false alarm probabilities and (3) subcarrier pairing for transmission on the SU transmitter and the cognitive relay and (4) minimum Quality of Service (QoS) for each CR subcarrier. We propose one optimal and two sub-optimal schemes all of which are compared to other schemes in the literature. Simulation results show that the proposed schemes achieve significantly higher throughput than other schemes in the literature for different relay situations.Comment: EAI Endorsed Transactions on Wireless Spectrum 14(1): e4 Published 13th Apr 201

Mechanical Characterization of Torsional Micropaddles Using Atomic Force Microscopy

The reference cantilever method is shown to act as a direct and simple method for determination of torsional spring constant. It has been applied to the characterization of micropaddle structures similar to those proposed for resonant functionalized chemical sensors and resonant thermal detectors. It is shown that this method can be used as an effective procedure to characterize a key parameter of these devices and would be applicable to characterization of other similar MEMS/NEMS devices such as micromirrors. In this study, two sets of micropaddles are manufactured (beams at centre and offset by 2.5 μm) by using LPCVD silicon nitride as a substrate. The patterning is made by direct milling using focused ion beam. The torsional spring constant is achieved through micromechanical analysis via atomic force microscopy. To obtain the gradient of force curve, the area of the micropaddle is scanned and the behaviour of each pixel is investigated through an automated developed code. The experimental results are in a good agreement with theoretical results

Stationary Josephson effect in a weak-link between nonunitary triplet superconductors

A stationary Josephson effect in a weak-link between misorientated nonunitary triplet superconductors is investigated theoretically. The non-self-consistent quasiclassical Eilenberger equation for this system has been solved analytically. As an application of this analytical calculation, the current-phase diagrams are plotted for the junction between two nonunitary bipolar $f-$wave superconducting banks. A spontaneous current parallel to the interface between superconductors has been observed. Also, the effect of misorientation between crystals on the Josephson and spontaneous currents is studied. Such experimental investigations of the current-phase diagrams can be used to test the pairing symmetry in the above-mentioned superconductors.Comment: 6 pages and 6 figure

Self-similar disk packings as model spatial scale-free networks

The network of contacts in space-filling disk packings, such as the Apollonian packing, are examined. These networks provide an interesting example of spatial scale-free networks, where the topology reflects the broad distribution of disk areas. A wide variety of topological and spatial properties of these systems are characterized. Their potential as models for networks of connected minima on energy landscapes is discussed.Comment: 13 pages, 12 figures; some bugs fixed and further discussion of higher-dimensional packing

Transport Properties in Ferromagnetic Josephson Junction between Triplet Superconductors

Charge and spin Josephson currents in a ballistic superconductor-ferromagnet-superconductor junction with spin-triplet pairing symmetry are studied using the quasiclassical Eilenberger equation. The gap vector of superconductors has an arbitrary relative angle with respect to magnetization of the ferromagnetic layer. We clarify the effects of the thickness of ferromagnetic layer and magnitude of the magnetization on the Josephson charge and spin currents. We find that 0-\pi transition can occur except for the case that the exchange field and d-vector are in nearly perpendicular configuration. We also show how spin current flows due to misorientation between the exchange field and d-vector.Comment: 6 pages, 8 figure

Pancreatic anastomosis training models:current status and future directions

Postoperative pancreatic fistula (POPF) is a major cause of morbidity and mortality after pancreatoduodenectomy (PD), and previous research has focused on patient-related risk factors and comparisons between anastomotic techniques. However, it is recognized that surgeon experience is an important factor in POPF outcomes, and that there is a significant learning curve for the pancreatic anastomosis. The aim of this study was to review the current literature on training models for the pancreatic anastomosis, and to explore areas for future research. It is concluded that research is needed to understand the mechanical properties of the human pancreas in an effort to develop a synthetic model that closely mimics its mechanical properties. Virtual reality (VR) is an attractive alternative to synthetic models for surgical training, and further work is needed to develop a VR pancreatic anastomosis training module that provides both high fidelity and haptic feedback

VirtuWind: Virtual and Programmable Industrial Network Prototype Deployed in Operational Wind Park

With anticipated exponential growth of connected devices, future industrial networks require an open solutions architecture facilitated by standards and a strong ecosystem.VirtuWind aims to develop and demonstrate an SDN and NFV ecosystem, based on an open, modular and secure framework.A prototype of the framework for intra-domain and inter-domain scenarios will be showcased in real wind parks,as a representative use case of industrial networks. Validate the economic viability of the demonstrated solution is paramount for VirtuWind. This paper details this vision and explains steps forward

Assessment of noise induced psychological stresses on printery workers

The purpose of this study was to assess the relationship between psychological stresses and noise stresses on printery workers in Tehran, Iran. Hence, 267 workers were randomly selected. The Leq and Lmax were measured and the psychological stresses such as depression, anxiety, aggression and job satisfaction were also studied by the relevant questionnaires. The data were statistically analyzed by Pearson correlation test. The results demonstrated that there was no significant statistical relationship between noise and psychological stresses. In addition, by using Spearman regression method, the influence of variables such as age, gender and job history on psychological stresses caused by Leq and Lmax was studied and the results only revealed that the aggression caused by Leq increased in young personnel (P=0.02) as well as, anxiety caused by Lmax increased accompanied by increasing the job history and age of the workers (P=0.002 and P=0.007). Therefore, more variables must be taken into consideration to judge about noise induced psychological stresses in workplaces. © IRSEN, CEERS, IAU