Co 3 O 4 nanorods have been successfully synthesized by thermal decomposition of the precursor prepared via a facile and efficient microwave-assisted hydrothermal method, using cetyltrimethylammonium bromide (CTAB) with ordered chain structures as soft template for the first time. The obtained Co 3 O 4 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical measurements. The results demonstrate that the as-synthesized nanorods are single crystalline with an average diameter of about 20 to 50 nm and length up to several micrometers. Preliminary electrochemical studies, including cyclic voltammetry (CV), galvanostatic chargedischarge, and electrochemical impedance spectroscopy (EIS) measurements, are carried out in 6 M KOH electrolyte.

Mechanical transmission systems have been widely adopted in most of industrial applications, and issues related to the maintenance of these systems have attracted considerable attention in the past few decades. The recently developed ensemble local mean decomposition (ELMD) method shows satisfactory performance in fault detection of mechanical components for preventing catastrophic failures and reducing maintenance costs. However, the performance of ELMD often heavily depends on proper selection of its model parameters. To this end, this paper proposes an optimized ensemble local mean decomposition (OELMD) method to determinate an optimum set of ELMD parameters for vibration signal analysis. In OELMD, an error index termed the relative root-mean-square error (Relative RMSE) is used to evaluate the decomposition performance of ELMD with a certain amplitude of the added white noise. Once a maximum Relative RMSE, corresponding to an optimal noise amplitude, is determined, OELMD then identifies optimal noise bandwidth and ensemble number based on the Relative RMSE and signal-to-noise ratio (SNR), respectively. Thus, all three critical parameters of ELMD (i.e. noise amplitude and bandwidth, and ensemble number) are optimized by OELMD. The effectiveness of OELMD was evaluated using experimental vibration signals measured from three different mechanical components (i.e. the rolling bearing, gear and diesel engine) under faulty operation conditions.

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A time scale is a procedure for accurately and continuously marking the passage of time. It is exemplified by Coordinated Universal Time (UTC), and provides the backbone for critical navigation tools such as the Global Positioning System (GPS). Present time scales employ microwave atomic clocks, whose attributes can be combined and averaged in a manner such that the composite is more stable, accurate, and reliable than the output of any individual clock. Over the past decade, clocks operating at optical frequencies have been introduced which are orders of magnitude more stable than any microwave clock. However, in spite of their great potential, these optical clocks cannot be operated continuously, which makes their use in a time scale problematic. In this paper, we report the development of a hybrid microwave-optical time scale, which only requires the optical clock to run intermittently while relying upon the ensemble of microwave clocks to serve as the flywheel oscillator. The benefit of using clock ensemble as the flywheel oscillator, instead of a single clock, can be understood by the Dick-effect limit. This time scale demonstrates for the first time sub-nanosecond accuracy for a few months, attaining a fractional frequency stability of 1.45×10 −16 at 30 days and reaching the 10 −17 decade at 50 days, with respect to UTC. This time scale significantly improves the accuracy in timekeeping and could change the existing time-scale architectures.

We demonstrate a Cs FADOF (Faraday anomalous dispersion optical filter) with a single transmission peak resonant with the 6S(1/2), F = 4 → 7P(3/2), F' = 3, 4, 5 transition at 455 nm. The filter achieves a single peak transmission of 86%. With the technique of saturated absorption spectra, we obtain the bandwidth of the single peak, which is 1.5 GHz. While most of other FADOFs operate at frequencies far from absorption, the filter we have realized can provide light exactly resonant with atomic transitions with a high transmission. We also find that, at a particular temperature, we can achieve a single transmission peak rather than many peaks far from absorption by changing the strength of magnetic field. This technique can also be applied to other alkali atoms.

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We find the one-way mode can be well-confined at the magnetic domain wall by the photonic bandgap of gyromagnetic bulk material. Utilizing the well-confined one-way mode at the domain wall, we demonstrate the photonic one-way waveguide, splitter and bender can be realized with simple structures, which are predicted to be high-efficiency, broadband, frequency-independent, reflection-free, crosstalk-proof and robustness against disorder. Additionally, we find that the splitter and bender in our proposal can be transformed into each other with magnetic control, which may have great potential applications in all photonic integrated circuit.One-way waveguide has been drawn much attention in recent years 1-11 , for their great potential application in all photonic integrated circuit. A popular solution for one-way waveguide is utilizing the gyromagnetic photonic crystal 7,8 , which can support a chiral edge state that exhibits an anomalous unique directionality. Due to the unidirectionality of chiral edge state, the one-way waveguide can be realized via confinement of the surface states 7,8 . Such one-way photonic crystal waveguides with chiral edge state has been proven to exhibit strong robustness against disorder 9,10 . However, the one-way photonic crystal waveguides need complex structures, which may bring more challenges in integrated circuits. In addition, the existing one-way photonic crystal waveguides are all frequency-sensitive. To avoid these difficulties, very recently, another solution for one-way propagation has been proposed 12 , in which a broadband one-way mode (OWM) is predicted to propagate along a magnetic domain wall. However, the cost of the solution is the broadband OWM may be not suitable for one-way waveguide, since the mode extends into the bulk rather than confinement at the domain wall.In reviewing these existing efforts, we feel desirable to find a design for one-way waveguide that should include at least three characteristics: (I) simple structure; (II) broadband working frequency; and (III) well-confined mode in the waveguide. In this Letter, we will present our design to serve this purpose.Our design is based on the domain wall. The key of this work is to find a confinement mechanism to localize the broadband OWM at the domain wall. We find the OWM can be confined well at the domain wall via the photonic bandgap of bulk material 13,14 , unlike the oneway photonic crystal waveguides 7,8 confining the OWM in waveguide by the photonic bandgap of gyromagnetic photonic crystal.Utilizing the OWM well-confined at the domain wall, an one-way waveguide with a simple structure and broada) Electronic band working frequency can be realized. Such OWM makes the one-way waveguide high-efficiency and very robust against disorder. Besides one-way waveguide, the OWM localized at domain wall can also be used to design high-efficiency, crosstalk-proof splitters and benders. Additionally, with magnetic controlling, the splitter and bender can be transformed into each other in our proposal, which may have gr...