Search

In this paper, we report the positive bias temperature instability (PBTI) effects of the back-gated MoS2 n-MOSFET with Al2O3 gate dielectric. Multilayer MoS2 was used and all measurements are carried in vacuum to avoid the electric signal contamination by the top MoS2 surface water or oxygen molecules absorption. In the stress phase, the Id-Vg curve shifts to the positive gate bias direction. In the recovery phase, the Id-Vg shifts back completely to the fresh device curve. This indicates that voltage shift is purely due to trapping or detrapping of the oxide border traps at the MoS2/Al2O3 interface and no new traps are generated during the stress time. When applying different stress voltage and measuring the Id-Vg shift, we can calculate the oxide border trap energy density Ξ(E), which has a peak value of 6×1013cm−2eV−1 at 0.035eV above EC of MoS2 conduction band.

The article introduces a new switch-mode power amplifier based on a cascade multilevel topology. By adopting an advanced technology to achieve class D power amplifier multipulse PWM generator by FPGA, the amplifier enjoys a switching frequency which is 2N times of that of a single unit. The PWM trigger gathers A/D transform modulated wave by data acquiring unit, produces multi-channels phase-shifted triangle carrier waves and their reversed carrier waves by multi-channels phase-shifted triangle carrier waves control unit. The PWM trigger generates PWM trigger signals by compare control unit and deal with dead area protecting control by dead area control unit. The amplifier improves the output signal quality through dual current and voltage closed-loop control. The article lays emphasis on designing dual closed-loop control and the experiment results show that the proposed amplifier has a wide bandwidth, good instant response and high output quality.

In this paper a new kind of the strengthening buffer operators is established to expand the research of buffer operators in grey systems, and it's feasibility and effectiveness are confirmed by an numerical example. Furthermore, the problem of contradictions between quantitative analysis and qualitative analysis in pretreatment for vibration data sequences is also resolved effectively. The paper is divided into five sections including introduction of the basic grey system theory and the motivation of this research, the establishment of the basic concepts, the construction of strengthening buffer sequences and their characteristics, numerical example demonstration and final conclusions.

In this paper the value trends of the development coefficient is studied using the grey system theory for the dynamic development coefficient. After a brief introduction of grey system theory, the coefficient trend analysis and the dynamic development coefficient analysis using the grey system are discussed consequently. Next two numerical examples are used to demonstrate the proposed method.

Numerical method which can accurately predict pump’s performance has been obtained in this paper. Flow in centrifugal pump equipped with a conical suction, a conical suction with swirl stop, and a center baffle suction has been simulated respectively. With comparison of the pump performance curves, it indicates that the three suctions almost have the same effect to the pump, and the center baffle suction has worse performance. The flow structure at partial flow rate in the pumps is simulated in this paper too, and serious back flow is found in the flow passage of the impeller. Amounts of water flows back to the impeller inlet so that the uniformity of the inflow is disordered. Then the back flow occupies the whole flow passage and the flow is nearly cut off.

To increasing the prediction accuracy, the existing buffer operators are almost from the perspective of the average value processing the data. In this paper, a kind of new strengthening buffer operator is defined, and through example, the new strengthening buffer operators are confirmed that it's feasible and effective, superior to the simulation predicted when the sequence data have a sharp change from low growth to high-growth.

We investigate the mode characteristics for the two coupled microdisks by finite-difference time-domain (FDTD) technique. The numerical results show that the coupled first order whispering-gallery modes (WGMs) can couple with the coupled second order WGMs when their wavelengths approach each other. Q-factors of the coupled first order WGMs greatly decrease due to such mode coupling. The simulated time variation of mode field pattern also verifies the mode coupling between the first and the second coupled WGMs.

The characteristics for the twin coupled microdisks are investigated by finite-difference time-domain (FDTD) technique. In the twin coupled microdisks, mode coupling between the same order whispering-gallery modes (WGMs) results in coupled WGMs with split mode wavelengths and different quality factor (Q-factor). The numerical results show that the coupling between the first and the second order WGMs exists, which can greatly decrease the quality factor of the coupled first order WGMs and deduce the anti- crossing of the mode wavelength. Furthermore, we can see the coupling phenomenon from the field distribution varies with the gap.