Characteristic analysis of photonic crystal resonant cavity in the terahertz region

In this letter, a kind of two-dimensional photonic crystal structure applicable to THz devices is designed, and how to form a microcavity in this structure is discussed. The primary properties of the resonant cavity are analyzed, in which plane wave expansion method is used to make the calculation and the simulation. We've studied the variation of the bandgap structure and resonant frequency in THz region by changing the parameters, such as lattice constant, dielectric constant contrast and filling factor. The research results provided theoretical support for manufacturing the THz devices and the application of THz system.

Study on properties of tetrapod-like zinc oxide whisker/silicone rubber foam composites

In this paper, the microcellular silicone rubber foams, strengthened with tetrapod-like Zinc Oxide whisker（T-ZnOw） are prepared. Through further characterization, it can be seen that the average cell diameter size of the filled with T-ZnOw is reduced. The distribution uniformity of microcellulars is improved obviously with increasing T-ZnOw filler. The reason that introduction of T-ZnOw can greatly enhance mechanical properties of the microcellular silicone rubber foams is its good interfacial adhesion with the matrix contributes. It is also found that the reducing effects of T-ZnOw on the compressive stress relaxation ratio of microcellular silicone rubber foams, and the improvement is obvious with increasing T-ZnOw filler.

A new dimmer for alternating-current directly driven light-emitting-diode lamp

A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.

Austenite Grain Growth Behavior of X80 Pipeline Steel in Heating Process

在Through changing soaking temperature and soaking time, austenite grain growth behavior of X80 pipeline steel under different heating conditions was studied. Relationships of average grain size to soaking temperature and time were obtained respectively. The results show that the prior austenite grains grow with the increase of soaking temperature and time. When soaking temperature is lower than 1 180 ℃, austenite grain size and growth rate are small; when it higher than 1 200 ℃, austenite grains grow rapidly and abnormal grain growth appears. For soaking at 1 180 ℃, austenite grain growth rate is initially high and then decreases when soaking time exceeds 1 h.

Constrained lattice density functional theory and its applications on vapor–liquid nucleations

Vapor-liquid phase transition occurs via a nucleation process, and depending on the role of foreign objects, nucleation can be either homogeneous or heterogeneous. In this review, we focus on the recently developed constrained lattice density functional theory （CLDFT） and its applications on vapor-liquid nucleation. We also review the recent theoretical advance on the stability of nanobubbles. Based on CLDFT, a pinning and supersaturation mechanism has proposed to interpret the surprising stability of surface nanobubbles. The mechanism can interpret most characteristics of nanobubbles. More importantly, the mechanism suggests that the critical nucleus can be stabilized under the condition of contact line pinning. Thus, CLDFT studies provide an alternative way to measure the critical nucleus that is difficult to measure experimentally in the bulk solution, through stabilizing it with surface roughness or heterogeneities.