Performance Analysis of Relay Based NOMA Cooperative Transmission under Cognitive Radio Network

This paper proposes a hybrid spectrum accessing mechanism by using NOMA-based cooperative transmission and beam-forming technology.In this mechanism,the secondary user employs spectrum-sensing technology to detect the existence of the primary user.If the primary user does not exist,the secondary source user directly transmits data to the destination user.If the primary user exists,the secondary source user finds the optimal relay according to certain selection principle before transmitting data to the destination user through the chosen relay node.For the signal receiving stage,the secondary user takes use of beam-forming technology to receive the signal from both the secondary source and the secondary relay node.Meanwhile the interference from the primary user is cancelled out in the stage.Furthermore,the outage probability for secondary user in the proposed mechanism is theoretically derived.Finally,the simulation results show that compared with the traditional mechanism,the proposed system model can not only guarantee the continuity of secondary transmission,but also significantly reduce the outage probability of secondary transmission.

A buried submarine canyon in the northwestern South China Sea: architecture, development processes and implications for hydrocarbon exploration

High-resolution multichannel seismic data enables the discovery of a previous,undocumented submarine canyon(Huaguang Canyon)in the Qiongdongnan Basin,northwestern South China Sea.The Huaguang Canyon with a NW orientation is 140 km in length,and 2.5 km to 5 km in width in its upper reach and 4.6 km to 9.5 km in width in its lower reach.The head of the Huaguang Canyon is close to the Xisha carbonate platform and its tail is adjacent to the Central Canyon.This buried submarine canyon is formed by gravity flows from the Xisha carbonate platform when the sea level dropped in the early stage of the late Miocene(around 10.5 Ma).The internal architecture of the Huaguang Canyon is mainly characterized by high amplitude reflections,indicating that this ancient submarine canyon was filled with coarse-grained sediments.The sediment was principally scourced from the Xisha carbonate platform.In contrast to other buried large-scale submarine canyons(Central Canyon and Zhongjian Canyon)in the Qiongdongnan Basin,the Huaguang Canyon displays later formation time,smaller width and length,and single sediment supply.The coarse-grained deposits within the Huaguang Canyon provide a good environment for reserving oil and gas,and the muddy fillings in the Huaguang Canyon have been identified as regional caps.Therefore,the Huaguang Canyon is a potential area for future hydrocarbon exploration in the northwestern South China Sea.The result of this paper may contribute to a better understanding of the evolution of submarine canyons formed in carbonate environment.

A buried submarine canyon in the northwest South China Sea:architecture,development processes and implications for hydrocarbon exploration

High-resolution multichannel seismic data enables the discovery of a previous,undocumented submarine canyon(Huaguang Canyon)in the Qiongdongnan Basin,northwest South China Sea.The Huaguang Canyon with a NW orientation is 140 km in length,and 2.5 km to 5 km in width in its upper reach and 4.6 km to 9.5 km in width in its lower reach.The head of the Huaguang Canyon is close to the Xisha carbonate platform and its tail is adjacent to the central canyon.This buried submarine canyon is formed by gravity flows from the Xisha carbonate platform when the sea level dropped in the early stage of the late Miocene(~10.5 Ma).The internal architecture of the Huaguang Canyon is mainly characterized by high amplitude reflections,indicating that this ancient submarine canyon was filled with coarse-grained sediments.The sediment was principally scourced from the Xisha carbonate platform.In contrast to other buried large-scale submarine canyons(central canyon and Zhongjian Canyon)in the Qiongdongnan Basin,the Huaguang Canyon displays later formation time,smaller width and length,and single sediment supply.The coarse-grained deposits within Huaguang Canyon provide a good environment for reserving oil and gas,and the muddy fillings in Huaguang Canyon have been identified as regional caps.Therefore,Huaguang Canyon is potential area for future hydrocarbon exploration in the northwest South China Sea.Our results may contribute to a better understanding of the evolution of submarine canyons formed in carbonate environment.

Classification and Research of Skin Lesions Based on Machine Learning

Classification of skin lesions is a complex identification challenge.Due to the wide variety of skin lesions,doctors need to spend a lot of time and effort to judge the lesion image which zoomed through the dermatoscopy.The diagnosis which the algorithm of identifying pathological images assists doctors gets more and more attention.With the development of deep learning,the field of image recognition has made long-term progress.The effect of recognizing images through convolutional neural network models is better than traditional image recognition technology.In this work,we try to classify seven kinds of lesion images by various models and methods of deep learning,common models of convolutional neural network in the field of image classification include ResNet,DenseNet and SENet,etc.We use a fine-tuning model with a multi-layer perceptron,by training the skin lesion model,in the validation set and test set we use data expansion based on multiple cropping,and use five models’ensemble as the final results.The experimental results show that the program has good results in improving the sensitivity of skin lesion diagnosis.