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This paper investigates the massive access for a satellite-aerial-terrestrial network (SATN), where a high-altitude platform (HAP) is deployed as a relay to assist the uplink transmission from terrestrial user equipment (UE) to satellite. Unlike previous works, we adopt radio frequency (RF) and free space optical for the aerial-terrestrial and satellite-aerial links, respectively. Specifically, by assuming that imperfect angular information (IAI) of each UE is known at the HAP, we develop a space division multiple access (SDMA) scheme to maximize the ergodic sum rate (ESR). To this end, we first exploit the IAI to calculate the analytical expression of channel correlation matrix. Then, by considering the limitation of array freedom, we propose a subspace-based UE grouping and scheduling scheme to cluster all UEs into groups. Next, we present a computationally effective beamforming (BF) scheme for each UE at HAP to efficiently implement SDMA in the RF link. Furthermore, a closed-form expression for the ESR of the SATN is derived to validate the proposed BF and SDMA schemes. Finally, simulation results corroborate the derived theoretical formulas and reveal the impacts of array size, angular estimation error, the number of UEs and scheduling threshold on the system performance. [ABSTRACT FROM AUTHOR]

In this article, we investigate the performance of a multiuser integrated satellite-terrestrial relay network (ISTRN) with the threshold-based decode-and-forward protocol, where the satellite-relay link undergoes shadowed-Rician (SR) fading, while the relay-user links experience Nakagami-m fading. We first formulate a constrained optimization problem with an objective to maximize the system capacity in order to determine the beamforming weight vectors at the relay and thereby develop two multiuser scheduling schemes, namely, best user scheduling and user fairness scheduling. Then, we present a closed-form expression for the probability density function (PDF) of the square sum of independent and identically distributed SR random variables, which is more accurate and concise than the existing solutions. Based on the new PDF results, we derive closed-form expressions for the outage probability (OP) and ergodic capacity of the considered network using the two scheduling schemes. Furthermore, the asymptotic OP expressions at high signal-to-noise ratio are also deduced to reveal the asymptotic behavior of the considered ISTRN. Finally, simulation results are provided to validate our theoretical analysis and show the impact of various parameters on the system performance. [ABSTRACT FROM AUTHOR]

In this paper, we investigate energy efficient transmission for a satellite-aerial-terrestrial network (SATN), where a multi-antenna unmanned aerial vehicle (UAV) is employed as a relay to assist the satellite signal delivery. By considering total power constraint (TPC) or per-antenna power constraint (PPC) at the UAV, we first formulate an optimization problem to maximize the energy efficiency of the SATN, which is defined as ratio of the ergodic capacity to the total power consumption for communication at UAV. Then, by jointly exploiting array signal processing with the Dinkelbach’s method, two new beamforming (BF) schemes, namely, TPC-BF and PPC-BF are proposed to solve the non-convex energy efficiency maximization problem. The main advantage of our method is that only angular information-based channel state information is used to obtain BF weight vectors so that a low implementation complexity is achieved. Furthermore, by assuming that the satellite-UAV link undergoes correlated Shadowed-Rician fading while the UAV-terminal link experiences correlated Rician fading, closed-form expressions for the statistics of the equivalent output signal-to-noise ratio are derived and, thus energy efficiency for the considered SATN with BF schemes is analytically presented. Finally, simulation results corroborate the derived expressions and confirm the effectiveness of the proposed BF schemes. [ABSTRACT FROM AUTHOR]

A mesoporous Sn/SnO2 composite has been synthesized by a self-templating pore formation process at room temperature without any external templates. When evaluated as an anode for sodium-ion batteries, the composite material exhibited stable performance and high Coulombic efficiency, in addition to excellent rate performance. [ABSTRACT FROM AUTHOR]

Studies the electrochemical behavior of adriamycin (ADM) at cobalt/glassy carbon electrode (Co/GCE) ion implantation modified electrode. Preparation of ion implantation modified electrode Co/GCE; Comparison of the behaviors of Co/GCE and GCE; Effect of scan rate on catalytic efficiency.

• A red-peel Actinidia arguta mutant, CG 1, was identified from a bud sport of a green-peel A. arguta 'ZG 15′. • A variation in CG 1 was detected by SSR molecular marker analysis. • The total contents of anthocyanins in peel and pulp tissues of the mutant were both significantly higher comparing with that of the wild type. • Five differentially expressed genes were considered to be key genes contributing to the high accumulation level of anthocyanins in fruit of the mutant. Actinidia arguta is an important kind of kiwifruit species with good fruit quality and high economic value. New cultivars of kiwi berry and kiwifruit with high accumulation of anthocyanins in fruit are becoming more and more popular mainly due to the benefit of anthocyanins to human health. Here, a red-peel A. arguta mutant, CG 1, was identified, and its fruit quality was determined. The genetic variation of CG 1 was confirmed by kiwifruit Simple Sequence Repeats (SSR) molecular marker analysis. The peel color of mature fruit in this mutant changed into red, while it was green for the wild type. In addition, the total contents of anthocyanins in peel and pulp tissues of the mutant were both significantly higher when comparing with that of the wild type. Especially, the amount of anthocyanins in fruit peel of CG 1 was 7.49 mg g−1 fresh weight (FW), almost 9.4 times higher than that of the wild type. Further study by transcriptome sequencing and quantitative real-time PCR (qRT-PCR) analysis indicated that the expression patterns of five genes involved in anthocyanin biosynthesis were highly consistent with the anthocyanins contents in peel tissues of the two genotypes. We deduce that those five candidate genes are responsible for the high accumulation of anthocyanins in fruit of the red-peel kiwi berry mutant. This research provides useful methods to identify new kiwi berry mutant. And the comprehensive analysis reveals that the promoted anthocyanins accumulation in the mutant is dependent on the high transcriptional regulations of several key genes involved in anthocyanin biosynthesis pathway. [ABSTRACT FROM AUTHOR]

In this study, we investigate the outage probability (OP) of a multiuser dual-hop satellite relaying system with decode-and-forward (DF) protocol, where both uplink and downlink experience Shadowed Rician (SR) fading. Specifically,by taking the effects of antenna pattern and path loss into account, we first establish a practical satellite channel model and obtain the end-to-end signal-to-noise ratio (SNR) expression for the considered system, where the uplink employs opportunistic scheduling (OS) scheme while the downlink adopts selection combining (SC) or maximal ratio combining (MRC) approaches. Then, we derive the closed-form OP expressions for the dual-hop satellite relaying with OS/SC and OS/MRC schemes, respectively. Furthermore, the asymptotic OP formulas at high SNR are also developed to gain further insights conveniently. Finally, numerical results confirm the validity of the theoretical formulas and reveal the representative parameters on the system performance. [ABSTRACT FROM AUTHOR]

ABSTRACT A series of well-defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)- graft-poly( N-isopropylacrylate) (PGMA- g-PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self-assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co-relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA45- g-PNIPAM20 and PGMA45- g-PNIPAM46 with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA45- g-PNIPAM(73, 50%) shows a spherical-like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self-assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self-assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2442-2453 [ABSTRACT FROM AUTHOR]