Hybrid Phase-controlled Circuit Breaker with Switch System Used in the Railway Auto-passing Neutral Section with an Electric Load

Constrained by the characteristics of neutral sec- tions (NS) and traditional vacuum circuit breakers, previous phase-controlled strategies have a long power supply dead time, it is difficult to realize a continuous power supply to the auxiliary power system. The dead time can be reduced by using the ground automatic convert method, hybrid phase-controlled technologies can in theory completely eliminate inrush currents. In this paper, a new system based on hybrid phase-controlled switches is described and termed ground-switching passing neutral section system (GPNSS). The principle for restraining inrush currents is analyzed and strategies are carried out with the dead time limited to 5 ms. The characteristics of the vacuum circuit breaker are illustrated and the closing time window of the transformer is quantified. Through the use of mechanical switches and power electronics, the auxiliary power system may be continuously pow- ered. The prototype system is implemented and experimentally tested in the laboratory.

Controlling factors on the charging process of oil and gas in the eastern main sub-sag of the Baiyun Sag,Zhujiang River(Pearl River)Mouth Basin

The eastern main sub-sag(E-MSS)of the Baiyun Sag was the main zone for gas exploration in the deep-water area of the Zhujiang River(Pearl River)Mouth Basin at its early exploration stage,but the main goal of searching gas in this area was broken through by the successful exploration of the W3-2 and H34B volatile oil reservoirs,which provides a new insight for exploration of the Paleogene oil reservoirs in the E-MSS.Nevertheless,it is not clear on the distribution of“gas accumulated in the upper layer,oil accumulated in the lower layer”(Gas_(upper)-Oil_(lower))under the high heat flow,different source-rock beds,multi-stages of oil and gas charge,and multi-fluid phases,and not yet a definite understanding of the genetic relationship and formation mechanism among volatile oil,light oil and condensate gas reservoirs,and the migration and sequential charge model of oil and gas.These puzzles directly lead to the lack of a clear direction for oil exploration and drilling zone in this area.In this work,the PVT fluid phase,the origin of crude oil and condensate,the secondary alteration of oil and gas reservoirs,the evolution sequence of oil and gas formation,the phase state of oil and gas migration,and the configuration of fault activity were analyzed,which established the migration and accumulation model of Gas_(upper)-Oil_(lower)cocontrolled by source and heat,and fractionation controlled by facies in the E-MSS.Meanwhile,the fractionation evolution model among common black reservoirs,volatile reservoirs,condensate reservoirs and gas reservoirs is discussed,which proposed that the distribution pattern of Gas_(upper)-Oil_(lower)in the E-MSS is controlled by the generation attribute of oil and gas from source rocks,the difference of thermal evolution,and the fractionation controlled by phases after mixing the oil and gas.Overall,we suggest that residual oil reservoirs should be found in the lower strata of the discovered gas reservoirs in the oil-source fault and diapir-developed areas,while volatile oil reservoirs should be found in the deeper strata near the sag with no oil-source fault area.

Localization of a Three-Level Cascade Atom via Resonant Absorption

We show that it is possible to localize a three-level cascade atom under the resonance condition when it passes through a standing-wave field. The localization peaks appear at the nodes of the standing-wave field, the detecting probability is 50% in the subwavelength domain, and the peaks are narrower on the resonance than the off- resonance. The absorption is the same as that in the usual two-level medium at the nodes and is greatly suppressed outside the nodes due to the Autler-Townes splitting. This is in sharp contrast to the lambda scheme, in which the localization is impossible under the same resonance condition due to the depletion of population of the initial state by the probe field at the nodes and the electromagnetically induced transparency outside the nodes.

Electron-Helium Scattering in Free-Free Transitions in a Bichromatic Laser Field

Theoretical calculation of the differential cross section （DCS） for elastic electron-helium scattering in the presence of a bichromatic CO2 laser field is carried out in the first Born approximation with a simple screening electric potential. The two components of the laser field have the frequencies w and 2w, which are out of phase by an arbitrary scale φ. The variations of the differential cross section as a function of the phase angle φ in the domain 0°≤ φ ≤360° are presented. We discuss the influence of the number of photons exchanged on the phase-dependee effect. Moreover, for different scattering angles and incident electron energies, the DCS has outstanding ditferences. These illustrate that the two parameters have important effects on the differential cross section and the screening electric potential is effective.

一种超快的碲化法用于非常规相控碲化钯小纳米颗粒的合成

本研究发展了一种超快的碲化方法,可以在碳纳米管上快速制备非常规相控碲化钯小纳米颗粒.这种碲化方法只需要一台家用微波炉,整个过程非常快(60秒),简单,不含表面活性剂,可规模化生产.通过在相同条件下仅调整前驱体Te粉的使用量,可以精确调控合成小尺寸(约5.5 nm)、高产率(约90%)的六方结构PdTe/CNT和菱方结构Pd_(20)Te_7/CNT.其中,六方结构的PdTe/CNT在甘油氧化反应(GOR)和乙二醇氧化反应(EGOR)中表现出卓越的性能.具体来说,六方结构的PdTe/CNT在甘油氧化反应中,最高电流密度可达2.72 A mg_(Pd)^(-1),比菱方结构Pd_(20)Te_7/CNT的最高电流密度高1.9倍,比Pd/CNT最高电流密度高2.8倍,超过了目前文献中报道过的大多数催化剂.同时,六方结构的PdTe/CNT在乙二醇氧化反应中比活性达到3.65 A mg_(pd)^(-1),比菱方结构的Pd_(20)Te_7/CNT和Pd/CNT分别高2.1倍和3.9倍.我们希望这项工作可以为小尺寸非常规相控碲化物催化剂的制备提供新的碲化方法指导,并为相控材料的应用提供启发.

Phase engineering of metal-organic frameworks

As an important category of porous crystalline materials,metal-organic frameworks(MOFs)have attracted extensive research interests owing to their unique structural features such as tunable pore structure and enormous surface area.Besides controlling the size,dimensionality,and composition of MOFs,further exploring the crystal-phase-dependent physicochemical properties is essential to improve their performances in various applications.Recently,great progress has been achieved in the phase engineering of nanomaterials(PEN),which provides an effective strategy to tune the functional properties of nanomaterials by modulating the arrangement of atoms.In this review,we adopt“phase”instead of“topology”to describe the crystal structure of MOFs and summarize the recent advances in phase engineering of MOFs.The two main strategies used to control the phase of MOFs,that is,phasecontrolled synthesis and phase transformation of MOFs,will be highlighted.The roles of various reaction parameters in controlling the crystal phase of MOFs are discussed.Then,the phase dependence of MOFs in various applications including luminescence,adsorption,and catalysis are introduced.Finally,some personal perspectives about the challenges and opportunities in this emerging field are presented.