Backscatter Assisted NOMA-PLNC Based Wireless Networks

In this paper, sum capacity maximization of the non-orthogonal multiple access (NOMA)-based wireless network is studied in the presence of ambient backscattering (ABS). Assuming that ABS is located next to far nodes, it improves the signal strength of far node cluster. By applying suitable successive interference cancellation (SIC) operation, far node cluster act as an internet of things (IoT) reader. Moreover, to improve the uplink performance of the nodes, a physical layer network coding (PLNC) scheme is applied in the proposed network. Power optimization is employed at the access point (AP) to enhance the downlink performance with total transmit power constraint and minimum data rate requirement per user constraint using Lagrangian’s function. In addition, end-to-end outage performance of the proposed wireless network is analyzed to enhance each wireless link capacity. Numerical results evident that the outage performance of the proposed network is significantly improved while using the ABS. Furthermore, the average bit error rate (BER) performance of the proposed wireless network is studied to improve the reliability. Simulation results are presented to validate the analytical expressions.

Review on nonlinearity effect in radio over fiber system and its mitigation

Modern communication generation for high data rate requirement is fifth generation. The fifth generation has many advantages like low delay, high spectrum availability, high reliability, low jitter, and more capacity. To combat with the high capacity and high data rate requirement, optical fiber helps in the backhaul of 5G network. When fiber is used as a mode of propagation, many nonlinearities arises. This nonlinearity effect in the optical fiber communication is one of the most undesirable phenomena for the modern communication system which results in harmonic distortion, intermodulation distortion, phase distortion, and adjacent channel interference, etc. In most fiber optic communication systems, the major fiber nonlinear effect is the Kerr nonlinearity and Scattering effect that produced due to the variation of refractive index due to signal intensity. To minimize the effect of nonlinear distortion, some techniques are used which considerably improve the transmission capacity by reducing or compensating the effect of nonlinear distortion along with minimal infrastructure modifications and minimum cost for implementation. To overcome the effect of nonlinearity, fiber nonlinearity mitigation techniques are preferred to achieve the significant performance gains. Mitigation techniques can be implemented to improve and optimize the performance of optical communication network. In this paper, a brief description of the fiber nonlinearity effect and a review of various fiber nonlinearity compensation techniques are described.

Optimal 3D Deployment and Trajectory Selection of UAVs for Maximum Network Utility and Disaster Management

Advancement in Unmanned Aerial Vehicles (UAV) technology supervised us to use them in many situations like seismic survey of an area, border and restricted area surveillance, disaster rescue, agriculture monitoring, and many others. The deployment of UAVs for expansion and extension of wireless network coverage for surveillance and rescue during and post disaster situations is fenced with promising challenges. The dense user coverage, quality of service (QoS), user data rate requirement, limited short flying time, and optimal trajectory path are some of the pertinent issues that UAVs are encountering. In this work we develop some algorithms for fast deployment of UAVs for application in disaster scenarios and optimal trajectory of each UAV in some specified area. The main aim of the work is to reduce the time complexity for optimal deployment of UAVs in order to optimize diverse parametric constraints. We propose a highly time efficient algorithm for UAV deployment through Lloyd and FCM as the initial localization of position in conjunction with the evolutionary algorithm namely Differential Evolution (DE) and Hybrid Differential Evolution with Learning (HDEL) for finding the optimal location of UAVs. We also develop an algorithm for finding out the optimal trajectory to reach the intended location for effective deployment of UAVs to ensure optimal resource allocation and user coverage. Comprehensive simulation of various performance measuring metrics is obtained and the result shows that the proposed algorithms are well efficient as compared to some of the standard algorithms used in deployment of UAVs.

Size selection of the Ambu AuraOnce laryngeal mask in Chinese men weighing >70 kg: a pilot study

Objective To collect computed tomography data of the laryngeal anatomy of Chinese men and to determine the feasibility of using the size 4 Ambu AuraOnce laryngeal mask (Ambu A/S, Copenhagen, Denmark) in Chinese men weighing >70 kg. Methods This prospective study involved men who underwent surgery from May 2018 to January 2019 at Jinshan Hospital. Pharyngeal and laryngeal parameters were measured by computed tomography. The laryngeal mask insertion success rate, requirement for tracheal tube insertion, laryngeal mask insertion time, fiberoptic bronchoscopy grading, air leakage pressure, and pharyngeal complications were analyzed. Results In a comparison of the size 4 and 5 Ambu AuraOnce devices, the first insertion success rate was 100% and 87% and the three-times insertion success rate was 100% and 93%, respectively, with no significant differences. However, the insertion time was significantly different at 19.6 ± 5.9 versus 31.1 ± 11.2 s, respectively, and the proportions of fiberoptic grading levels were also significantly different. There were no significant differences in the air leakage pressure or pharyngeal complications. Conclusion The size 4 Ambu AuraOnce is more adequate than the size 5 for Chinese men weighing >70 kg, with a shorter insertion time and higher fiberoptic bronchoscopic grading.

Prostatic urethral lift (UroLift): a real-world analysis of outcomes using hospital episodes statistics

Background To determine real-world outcomes of prostatic urethral lift (UroLift) procedures conducted in hospitals across England. Methods A retrospective observational cohort was identified from Hospital Episode Statistics data including men undergoing UroLift in hospitals in England between 2017 and 2020. Procedure uptake, patient demographics, inpatient complications, 30-day accident and emergency re-attendance rate, requirement for further treatment and catheterization were captured. Kaplan–Meier and hazard analysis were used to analyse time to re-treatment. Results 2942 index UroLift procedures from 80 hospital trusts were analysed; 85.3% conducted as day-case surgery (admitted to hospital for a planned surgical procedure and returning home on the same day). In-hospital complication rate was 3.4%. 93% of men were catheter-free at 30 days. The acute accident and emergency attendance rate within 30 days was 12.0%. Results of Kaplan Meier analysis for subsequent re-treatment (including additional UroLift and endoscopic intervention) at 1 and 2 years were 5.2% [95% CI 4.2 to 6.1] and 11.9% [10.1 to 13.6] respectively. Conclusions This real-world analysis of UroLift shows that it can be delivered safely in a day-case setting with minimal morbidity. However, hospital resource usage for catheterization and emergency hospital attendance in the first 30 days was substantial, and 12% required re-treatment at 2 years.

Optimal UAV's Deployment and Transmit Power Design for Two Users Uplink NOMA Systems

In order to fully utilize the spectrum resources, this work considers a unmanned aerial vehicle (UAV) uplink communication system based on non-orthogonal multiple access technology (NOMA), in which the UAV receives information from the ground users with a certain flying altitude. As an initial study, we consider a simplified setup with two ground users to draw some insightful results. Explicitly, we first formulate an optimization problem that maximizes the sum throughput subject to each user's transmit power constraint and their corresponding minimum transmission rate requirement. Then, both the optimal transmit power and UAV's deployment location are derived with the aid of employing the Karush-Kuhn-Tucher (KKT) conditions. Simulation results show that the proposed UAV's deployment scheme with the users' power allocation can achieve a higher sum throughput compared with two existing benchmark schemes.

Development of a DP980 steel with low cooling rate requirement

DP980 is a promising light-weightening material in car body. To avoid high investment of strong cooling system, a new DP980 steel with low cooling rate requirement was developed. The mechanical properties and microstructure were analyzed under different manufacturing process. It could be concluded that the chemical composition design should be reasonable and of low cost to achieve both high strength and also austenite to martensite transformation at low cooling rate. Strength increased with coiling temperature decreasing during hot rolling, and higher annealing temperature and lower over aging temperature were favourable to higher strength. The austenite-martensite transforming could be completed at even lower rapid cooling rate of 20°C/s. Through optimized manufacturing process parameters, the new DP steel product with good mechanical properties could be obtained successfully, which provided a new option for normal production line to produce ultra high strength steel.

Scaling tendency prediction in water injection well of K2 formation of C68 block

The K2 formation of C68 block is explored by injecting water to maintain formation pressure, but the continuous decrease of injection rate significantly reduces oil production. Therefore, it is important to predict scaling tendency of injected water in the formation. Firstly, ion composition of formation water and injected water was tested according to recommended practices in petroleum industry. Then, wellbottom temperature distribution of injection wells was simulated under injection water rate requirement of oilfield development. Furthermore, based on the “Oddo-Tomson” prediction model of inorganic scale, the scaling trend of water flooding in K2 formation is predicted according to the possible temperature and pressure. The research indicates that sulfate scale cannot be formed in C68 block and there is a slight possibility of carbonate scaling, which provides a basis to select the correct stimulation technology for increasing production.