Horizontal-Based Orchestration for Multi-Domain SFC in SDN/NFV-Enabled Satellite/Terrestrial Networks

It's promising to use Software-Defined Networking(SDN) and Network Functions Virtualization(NFV) to integrate satellite and terrestrial networks. To construct network service function chains in such a multi-domain environment, we propose a horizontal-based Multi-domain Service Function Chaining(Md-SFC) orchestration framework. In this framework, multi-domain orchestrators can coordinate with each other to guarantee the end-to-end service quality. Intra-domain orchestrators also coordinate SDN controllers and NFV management components to implement intra-domain service function chains. Based on this, we further propose a heuristic SFC mapping algorithm with a cooperative inter-domain path calculation method to map service function chains to infrastructures. In this method, master multi-domain orchestrator and intra-domain orchestrators coordinate to select proper inter-domain links. We compare the cooperative method with a naive uncooperative way that domains' topology information is provided to the master multi-domain orchestrator and it calculates the shortest inter-domain path between intra-domain service function chains directly. Simulation results demonstrate that our solution is feasible. It is able to construct end-to-end performance guaranteed service function chain by horizontal-based cooperation. The cooperative inter-domain path calculation method decreasesthe mapping load for the master orchestrator and gets the same end-to-end performance.

Distributed Contact Plan Design for Multi-Layer Satellite-Terrestrial Network

In multi-layer satellite-terrestrial network, Contact Graph Routing(CGR) uses the contact information among satellites to compute routes. However, due to the resource constraints in satellites, it is extravagant to configure lots of the potential contacts into contact plans. What's more, a huge contact plan makes the computing more complex, which further increases computing time. As a result, how to design an efficient contact plan becomes crucial for multi-layer satellite network, which usually has a large scaled topology. In this paper, we propose a distributed contact plan design scheme for multi-layer satellite network by dividing a large contact plan into several partial parts. Meanwhile, a duration based inter-layer contact selection algorithm is proposed to handle contacts disruption problem. The performance of the proposed design was evaluated on our Identifier/Locator split based satellite-terrestrial network testbed with 79 simulation nodes. Experiments showed that the proposed design is able to reduce the data delivery delay.

Organometallic perovskite single crystals grown on lattice-matched substrate for photodetection

In this work,we demonstrate that an organometallic perovskite(OP)single crystal for effective photodetection can be grown on a gold(Au)-decorated substrate using liquid phase epitaxy.The covered gold could both control the shape of the epitaxial layer and act as its electrodes.An MAPbCl3 single crystal and an MAPbBr1.5Cl1.5 single crystal were used as the substrate and the epitaxial layer,respectively.The device,with an Au-perovskite-Au structure,can be fully characterized.Due to the high-quality epitaxial layer,the maximum external quantum efficiency(EQE)value is over 60%under the voltage of
20 V.In addition,the response speed can reach 200 and 500 ns(ns)rise and fall,respectively.Our work provides an effective and promising method to fabricate efficient perovskite-based photodetectors.

The Ghd7 transcription factor represses ARE1 expression to enhance nitrogen utilization and grain yield in rice

The genetic improvement of nitrogen use efficiency(NUE)of crops is vital for grain productivity and sustainable agriculture.However,the regulatory mechanism of NUE remains largely elusive.Here,we report that the rice Grain number,plant height,and heading date7(Ghd7)gene genetically acts upstream of ABC1 REPRESSOR1(ARE1),a negative regulator of NUE,to positively regulate nitrogen utilization.As a transcriptional repressor,Ghd7 directly binds to two Evening Element-like motifs in the promoter and intron 1 of ARE1,likely in a cooperative manner,to repress its expression.Ghd7 and ARE1 display diurnal expression patterns in an inverse oscillation manner,mirroring a regulatory scheme based on these two loci.Analysis of a panel of 2656 rice varieties suggests that the elite alleles of Ghd7 and ARE1 have undergone diversifying selection during breeding.Moreover,the allelic distribution of Ghd7 and ARE1 is associated with the soil nitrogen deposition rate in East Asia and South Asia.Remarkably,the combination of the Ghd7 and ARE1 elite alleles substantially improves NUE and yield performance under nitrogen-limiting conditions.Collectively,these results define a Ghd7–ARE1-based regulatory mechanism of nitrogen utilization,providing useful targets for genetic improvement of rice NUE.