Delay Optimal Secrecy in Two-Relay Network

We consider a two-relay network in which a source aims to communicate a confidential message to a destination while keeping the message secret from the relay nodes. In the first hop, the channels from the source to the relays are assumed to be block-fading and the channel states change arbitrarily -possibly non-stationary and non-ergodic- across blocks. When the relay feedback on the states of the source-to-relay channels is available on the source with no delay, we provide an encoding strategy to achieve the optimal delay. We next consider the case in which there is one-block delayed relay feedback on the states of the source-to-relay channels. We show that for a set of channel state sequences, the optimal delay with one-block delayed feedback differs from the optimal delay with no-delayed feedback at most one block

To Obtain or not to Obtain CSI in the Presence of Hybrid Adversary

We consider the wiretap channel model under the presence of a hybrid, half duplex adversary that is capable of either jamming or eavesdropping at a given time. We analyzed the achievable rates under a variety of scenarios involving different methods for obtaining transmitter CSI. Each method provides a different grade of information, not only to the transmitter on the main channel, but also to the adversary on all channels. Our analysis shows that main CSI is more valuable for the adversary than the jamming CSI in both delay-limited and ergodic scenarios. Similarly, in certain cases under the ergodic scenario, interestingly, no CSI may lead to higher achievable secrecy rates than with CSI.Comment: 8 pages, 3 figure

Improved chemotaxis differential evolution optimization algorithm

The social foraging behavior of Escherichia coli has recently received great attention and it has been employed to solve complex search optimization problems.This paper presents a modified bacterial foraging optimization BFO algorithm, ICDEOA (Improved Chemotaxis Differential Evolution Optimization Algorithm), to cope with premature convergence of reproduction operator.In ICDEOA, reproduction operator of BFOA is replaced with probabilistic reposition operator to enhance the intensification and the diversification of the search space.ICDEOA was compared with state-of-the-art DE and non-DE variants on 7 numerical functions of the 2014 Congress on Evolutionary Computation (CEC 2014). Simulation results of CEC 2014 benchmark functions reveal that ICDEOA performs better than that of competitors in terms of the quality of the final solution for high dimensional problems

Experimental demonstration of an optimised PWM scheme for more even device electro-thermal stress in a 3-Level ANPC GaN inverter

GaN device as one potential power electronics device has been gained much attention recently. One of the power conversion systems, ANPC inverter using GaN HEMT is potentially considered to be prospective usage of low loss and high efficiency. In this work, we demonstrate one optimised PWM scheme aims at balancing the device electro-thermal stress based on Parma PWM to control 3-Level ANPC GaN inverter. The method is to decrease the loss for switches account for the large loss and increase the loss for switches with less thermal stress initially. The simulation and experimental results prove the effectiveness of the optimised PWM in controlling the loss distribution

Wildbook: Crowdsourcing, computer vision, and data science for conservation

Photographs, taken by field scientists, tourists, automated cameras, and incidental photographers, are the most abundant source of data on wildlife today. Wildbook is an autonomous computational system that starts from massive collections of images and, by detecting various species of animals and identifying individuals, combined with sophisticated data management, turns them into high resolution information database, enabling scientific inquiry, conservation, and citizen science. We have built Wildbooks for whales (flukebook.org), sharks (whaleshark.org), two species of zebras (Grevy's and plains), and several others. In January 2016, Wildbook enabled the first ever full species (the endangered Grevy's zebra) census using photographs taken by ordinary citizens in Kenya. The resulting numbers are now the official species census used by IUCN Red List: http://www.iucnredlist.org/details/7950/0. In 2016, Wildbook partnered up with WWF to build Wildbook for Sea Turtles, Internet of Turtles (IoT), as well as systems for seals and lynx. Most recently, we have demonstrated that we can now use publicly available social media images to count and track wild animals. In this paper we present and discuss both the impact and challenges that the use of crowdsourced images can have on wildlife conservation.Comment: Presented at the Data For Good Exchange 201

Growth and reproduction studies on gilthead seabream (Sparus aurata) in Beymelek Lagoon, Turkey

In the present study, age, growth, length-weight relationship and reproduction were investigated in gilthead seabream (Sparus aurata L., 1758) collected from Beymelek Lagoon (Antalya, Turkey) between February 2006 and July 2007. The age, total length and weight of samples ranged from 0+ to 4 years, 10.6 to 35.5cm, and 18 to 928g, respectively. Growth was described by the standard form of the von Bertalanffy growth equation and the estimated parameters were L∞ = 44.6cm, k = 0.394yr^-1 and t0 = -1.331yr. Length-weight relationship was determined as W=0.0174TL^2.9769 (R^2=0.965), and weight increased with size isometrically (b = 2.9769) for all fish. Sex inversion occurred mainly at 26 cm in total length and females reached sexual maturity at 28.5 cm. The spawning period was from December to February, while the gamete emission peaked in December