Productive Development of Scalable Network Functions with NFork

Despite decades of research, developing correct and scalable concurrent programs is still challenging. Network functions (NFs) are not an exception. This paper presents NFork, a system that helps NF domain experts to productively develop concurrent NFs by abstracting away concurrency from developers. The key scheme behind NFork's design is to exploit NF characteristics to overcome the limitations of prior work on concurrency programming. Developers write NFs as sequential programs, and during runtime, NFork performs transparent parallelization by processing packets in different cores. Exploiting NF characteristics, NFork leverages transactional memory and develops efficient concurrent data structures to achieve scalability and guarantee the absence of concurrency bugs. Since NFork manages concurrency, it further provides (i) a profiler that reveals the root causes of scalability bottlenecks inherent to the NF's semantics and (ii) actionable recipes for developers to mitigate these root causes by relaxing the NF's semantics. We show that NFs developed with NFork achieve competitive scalability with those in Cisco VPP [16], and NFork's profiler and recipes can effectively aid developers in optimizing NF scalability.Comment: 16 pages, 8 figure

The site conditions of the Guo Shou Jing Telescope

The weather at Xinglong Observing Station, where the Guo Shou Jing Telescope (GSJT) is located, is strongly affected by the monsoon climate in north-east China. The LAMOST survey strategy is constrained by these weather patterns. In this paper, we present a statistics on observing hours from 2004 to 2007, and the sky brightness, seeing, and sky transparency from 1995 to 2011 at the site. We investigate effects of the site conditions on the survey plan. Operable hours each month shows strong correlation with season: on average there are 8 operable hours per night available in December, but only 1-2 hours in July and August. The seeing and the sky transparency also vary with seasons. Although the seeing is worse in windy winters, and the atmospheric extinction is worse in the spring and summer, the site is adequate for the proposed scientific program of LAMOST survey. With a Monte Carlo simulation using historical data on the site condition, we find that the available observation hours constrain the survey footprint from 22h to 16h in right ascension; the sky brightness allows LAMOST to obtain the limit magnitude of V = 19.5mag with S/N = 10.Comment: 10 pages, 8 figures, accepted for publication in RA

Single-cell analysis reveals specific neuronal transition during mouse corticogenesis

Background: Currently, the mechanism(s) underlying corticogenesis is still under characterization.Methods: We curated the most comprehensive single-cell RNA-seq (scRNA-seq) datasets from mouse and human fetal cortexes for data analysis and confirmed the findings with co-immunostaining experiments.Results: By analyzing the developmental trajectories with scRNA-seq datasets in mice, we identified a specific developmental sub-path contributed by a cell-population expressing both deep- and upper-layer neurons (DLNs and ULNs) specific markers, which occurred on E13.5 but was absent in adults. In this cell-population, the percentages of cells expressing DLN and ULN markers decreased and increased, respectively, during the development suggesting direct neuronal transition (namely D-T-U). Whilst genes significantly highly/uniquely expressed in D-T-U cell population were significantly enriched in PTN/MDK signaling pathways related to cell migration. Both findings were further confirmed by co-immunostaining with DLNs, ULNs and D-T-U specific markers across different timepoints. Furthermore, six genes (co-expressed with D-T-U specific markers in mice) showing a potential opposite temporal expression between human and mouse during fetal cortical development were associated with neuronal migration and cognitive functions. In adult prefrontal cortexes (PFC), D-T-U specific genes were expressed in neurons from different layers between humans and mice.Conclusion: Our study characterizes a specific cell population D-T-U showing direct DLNs to ULNs neuronal transition and migration during fetal cortical development in mice. It is potentially associated with the difference of cortical development in humans and mice

Fractional-Order Sliding Mode Control Method for a Class of Integer-Order Nonlinear Systems

In this study, the problem of the stabilisation of a class of nonautonomous nonlinear systems was studied. First, a fractional stability theorem based on a fractional-order Lyapunov inequality was formulated. Then, a novel fractional-order sliding surface, which was a generalisation of integral, first-order, and second-order sliding surfaces with varying fractional orders, was proposed. Finally, a fractional-order sliding mode-based control for a class of nonlinear systems was designed. The stability property of the system with the proposed method was easily proven as a fractional Lyapunov direct method by the fractional stability theorem. As an illustration, the method was used as a fractional guidance law with an impact angle constraint for a manoeuvring target. Simulation results demonstrated the applicability and efficiency of the proposed method

4.5kV FRD Development for high current power modules

A 4.5kV/100A FRD was designed by simulation, which had optimized carrier density distribute cell and ruggedness terminal. The cell was composed of P-body/N-sub/N+ layers, when the P-body doping concentration is lower, the carrier density distribution on the P-body/N-sub is lower; when carrier density di stribution on the P-body/N-sub side is lower than that on the N-sub/N+ side, the FRD has soft recovery but bad surge-current capability. So the P-body doping concentration needs trade-off consideration. Lifetime control technology was also used to optimize the carrier density distribution and trade-off characteristics. The terminal has high breakdown voltage, low electric field and large process window, which means more ruggedness and high reliability. The experiment results show that the design chip and competitor chip has nearly the same trade-off characteristics, the design chip has larger dynamic loss but lower static loss. The design chip has high surge current, the surge current is 13 times as much as the rate current

4.5kV FRD Development for high current power modules

A 4.5kV/100A FRD was designed by simulation, which had optimized carrier density distribute cell and ruggedness terminal. The cell was composed of P-body/N-sub/N+ layers, when the P-body doping concentration is lower, the carrier density distribution on the P-body/N-sub is lower; when carrier density di stribution on the P-body/N-sub side is lower than that on the N-sub/N+ side, the FRD has soft recovery but bad surge-current capability. So the P-body doping concentration needs trade-off consideration. Lifetime control technology was also used to optimize the carrier density distribution and trade-off characteristics. The terminal has high breakdown voltage, low electric field and large process window, which means more ruggedness and high reliability. The experiment results show that the design chip and competitor chip has nearly the same trade-off characteristics, the design chip has larger dynamic loss but lower static loss. The design chip has high surge current, the surge current is 13 times as much as the rate current

Solution for the Drift Problem of the Chip in the Packaging Process

This paper analyzes the drift phenomenon of the chips appearing in the packaging process of the fast recovery diode (FRD), and proposes an effective process to solve this problem. In order to improve the trade-off characteristics of fast recovery diodes, lifetime control methods, such as electron irradiation, high-energy ion implantation and so on, are often introduced in the chip manufacturing process. The chips described in this paper use the lifetime control method of electron irradiation. The problem of chips drift during the packaging process has been found. In this paper, by comparing different back metal schemes, comparing and analyzing the products of different manufacturers, the cause of chips drift is ultimately located in the annealing process after electron irradiation. The result of this paper shows that the chips drift phenomenon can be solved by adjusting the process steps

Solution for the Drift Problem of the Chip in the Packaging Process

This paper analyzes the drift phenomenon of the chips appearing in the packaging process of the fast recovery diode (FRD), and proposes an effective process to solve this problem. In order to improve the trade-off characteristics of fast recovery diodes, lifetime control methods, such as electron irradiation, high-energy ion implantation and so on, are often introduced in the chip manufacturing process. The chips described in this paper use the lifetime control method of electron irradiation. The problem of chips drift during the packaging process has been found. In this paper, by comparing different back metal schemes, comparing and analyzing the products of different manufacturers, the cause of chips drift is ultimately located in the annealing process after electron irradiation. The result of this paper shows that the chips drift phenomenon can be solved by adjusting the process steps

Lithium Bis(fluorosulfony)imide-Lithium Hexafluorophosphate Binary-Salt Electrolytes for Lithium-Ion Batteries: Aluminum Corrosion Behaviors and Electrochemical Properties

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Aluminum corrosion behaviors and electrochemical properties of Lithium bis(fluorosulfony)imide (LiFSI)-lithium hexafluorophosphate (LiPF6) binary-salt electrolytes containing mixtures of LiFSI and LiPF6 (with a total salt content of 1.2 mol L−1) with different molar ratios in EC/EMC (3:7, by vol.) solutions are systematically investigated. Our experimental results from cyclic voltammetry, scanning electron microscopy (SEM), chronoamperometry and the charge-discharge measurements of Li/LiNi1/3Co1/3Mn1/3O2 half-cells demonstrate that the LiFSI-LiPF6 binary-salt electrolytes with the LiFSI concentrations lower than 0.3 mol L−1 exhibit not only passivating aluminum current collectors at 4.3 V vs. Li+/Li, but also improved cycling performance. Meanwhile, Artificial Graphite/LiNi1/3Co1/3Mn1/3O2 (AG/NMC111) pouch cells made with the LiFSI(0.2)-LiPF6 (1.0) electrolyte with the LiFSI concentration of 0.2 mol L−1 display an excellent cycling stability with 93.9% capacity retention at 1 C rate after 360 cycles, and enhanced capacity retention at −20 °C, 60 °C and after 55 °C storage for 30 days compared to cells with 1.2 mol L−1 LiPF6/EC-EMC conventional electrolyte. This work confirms that binary-salt electrolytes system, such as LiFSI-LiPF6, may be a promising method to enhance the longevity and storage properties of Li-ion batteries

Oxidation decomposition mechanism of fluoroethylene carbonate-based electrolytes for high-voltage lithium ion batteries: a DFT calculation and experimental study

The oxidative decomposition mechanism of fluoroethylene carbonate (FEC) used in high-voltage batteries is investigated by using density functional theory (DFT). Radical cation FEC•+ is formed from FEC by transferring one electron to electrode and the most likely decomposition products are CO2 and 2-fluoroacetaldehyde radical cation. Other possible products are CO, formaldehyde and formyl fluoride radical cations. These radical cations are surrounded by much FEC solvent and their radical center may attack the carbonyl carbon of FEC to form aldehyde and oligomers of alkyl carbonates, which is similar with the oxidative decomposition of EC. Then, our experimental result reveals that FEC-based electrolyte has rather high anodic stability. It can form a robust SEI film on the positive electrode surface, which can inhibit unwanted electrolyte solvent and LiPF6 salts decomposition, alleviate Mn/Ni dissolution and therefore, improve the coulombic efficiency and the cycling stability of high voltage LiNi0.5Mn1.5O4 positive electrodes. This work displays that FEC-based electrolyte systems have considerable potential replacement of the EC-based electrolyte for the applications in 5 V Li-ion batteries