多功能智能调节仪开关电源设计

针对多功能调节仪表电路的要求,采用TOPSWITCH芯片设计五路输出的AC-DC电源.重点介绍了电源原理电路、高频变压器的设计和调试中的关键问题,文中特别对调试过程中常遇到的启动问题、干扰的抑止问题等作了详细分析,并给出了解决方法,从而保证其输出纹波系数等性能指标.     

Tectonic control on peritidal carbonate parasequence formation: an investigation using forward tectono-stratigraphic modelling

Studies of Quaternary extensional faults indicate that they have instantaneous amounts of throw (0·4 to 4 m), average slip rates (0·05 to 2·8 m kyr⁻¹) and frequency of recurrence (<40 000 years) accounting for the accommodation space required for the accumulation of peritidal carbonate parasequences (PCPs). Hangingwall sites and graben are characterized by fault down-dropping together with regional subsidence, and footwall sites and horsts by fault-related uplift alternating with periods of regional subsidence. The relative sea-level curves generated by these processes operating in a maritime rift setting are used as inputs to a forward stratigraphic modelling program SedTec2000 to simulate how fault-related changes in accommodation space can account for high-frequency PCP formation. Each instantaneous fault slip generates a flooding surface or aggradation in hangingwall and graben settings. High-frequency cycles in hangingwall sites are either symmetric (deepening then shallowing upward) or asymmetric (shallowing-upward). The major factor controlling cycle types is the balance between rates of carbonate accumulation and generation of accomodation space. High-frequency cycles in footwall sites and horsts comprise shallow subtidal facies, with no distinctive bathymetric trends, capped by erosional boundaries generated by footwall uplift. The modelled cycles are of the same thickness, with bathymetric trends and frequency to cycles commonly interpreted to be due to orbitally driven eustatic sea-level changes or autocyclic processes. These numerical experiments demonstrate that high-frequency PCPs can be generated by tectonic, fault-related processes, a hypothesis that is frequently discounted.     

Representation of microscale ocean wavenumber spectrum correct to the second order

Up to now the finest synthetic aperture radar(SAR) sea surface image is still the state-of-art oceanimage provided by the satellite microwave remotesensing due to its high spatial resolution and dynamicremote sensing mechanism. Early in 1978, Valenzueladerived the analytical representation of SAR image(backscaterring cross section distribution) on the tem-porally stationary and locally homogeneous assump-tion[1] σ0 (θ)IJ = 4πkm cos4θ gIJ (θ) E0(k,0), (1) (1) …     

电磁式可控震源与大地耦合的研究

目前国内各大油田采用的可控震源 ,主要以车载液压式为主 ,频率低 ,重量大。耦合方式是把整车的重量压在激震器基板上 ,由于整车的重量远大于激振器的输出力 ,所以耦合效果较好。通过物理工程建模 ,研究了激震器所输出的力与底座、弹簧、配重的关系。使得实际工作中可以避免激震器与大地脱耦 ,实现在浅层地震勘探时将激震器产生的力最大限度的传入地下 ,并减少了系统的重量     

电磁驱动可控震源与夯击震源对比研究

地震勘探对地下地质结构的调查是一种行之有效的方法，但由于条件的限制，有些地区不适合采用炸药震源，而且炸药震源费用高，危险大，所以采用电磁驱动可控震源，为验证可控震源野外工作的稳定性，可靠性，有效性，在河北省迁安大石河铁矿进行了实际探测，通过与夯击震源对比，可控震源较夯击震源具有更高的分辨率，并可以自由选择频率范围。     

GNSS增强系统中精密实时钟差高频估计及应用研究

GNSS星基差分增强系统依赖于实时轨道及钟差增强信息。本文主要研究多GNSS实时精密钟差估计模型,在传统非差基础上优化待估参数,实现了一种高效的Multi-GNSS实时钟差简化估计模型。基于PANDA软件开展了实时轨道数据处理与分析,经过验证可获得的GPS/北斗MEO/Galileo实时轨道径向精度1~5cm,北斗GEO/IGSO卫星径向精度约10cm。分析发现本文优化的实时钟差简化估计模型单历元解算效率较高,可应用于实时钟差增强信息高频(如1Hz)更新,且解算获得的实时钟差不存在常偏为绝对钟差;基于实时轨道,通过该模型可获得实时钟差精度GPS约0.22ns,北斗GEO约0.50ns、IGSO/MEO约0.24ns,Galileo约0.32ns。在此基础上,利用目前所获取的MultiGNSS实时数据流搭建了Multi-GNSS全球实时增强原型系统,并基于互联网实时播发增强信息,可初步实现实时PPP厘米级服务、伪距米级导航定位服务。     

Wave setup at Tristan da Cunha

Wave setup was investigated using data from tide gauges in a small harbour at the island of Tristan da Cunha in the South Atlantic Ocean. Frequent examples of wave setup were found during the period 1986–1992, but were much less apparent after 1992, following extensions to the two breakwater arms of the harbour. The unambiguous association of wave setup with the several-decimetre spikes in Tristan sea level, which can persist for a day or so, are a warning that signals related to wave setup could also occur in other tide gauge records, where the wave setup signal could perhaps be misinterpreted as wind setup within the overall storm surge. One conclusion is that, in spite of the difficulties of access to Tristan da Cunha and its ever-present hostile wave climate, the island is undoubtedly now worthy of a permanent tide-gauge installation, which would be an important contribution to the global sea-level network.     

Geochemical Characteristics and Sedimentary Control of Pinghu Formation (Eocene) Coal‐bearing Source Rocks in Xihu Depression,East China Sea Basin

Coal-bearing source rocks of the Pinghu Formation in the Xihu Depression comprise an important material basis of oil and gas resources in the East China Sea Basin.Based on drilling core observation results combined with the analysis and test results of macerals,trace/rare earth elements,and rock pyrolysis,the geochemical characteristics and sedimentary control of coal-bearing source rocks formation are discussed in a high-frequency sequence framework.The results indicate that the macerals composition of the coal-bearing source rocks of the Eocene Pinghu Formation in the Xihu Depression is dominated by vitrinite,with low-medium abundance of exinite and almost no inertinite.The coals and carbonaceous mudstones display higher amounts of total organic carbon(TOC)(14.90%-65.10%),S1+S2(39.24-136.52 mg/g),and IH(191-310 HC/g TOC)respectively,as compared to the mudstones.Organic matter is plotted in typeⅢkerogens and partially in typeⅡ;it is mainly in the low maturity stage.The trace elements results imply that the samples were deposited in a weakly reducing to weakly oxidizing environment and were occasionally affected by seawater.The coal-bearing source rocks were deposited in a relatively oxygen-containing environment.The coal-bearing source rocks development is jointly controlled by the coal accumulation environment,the water conditions affected by ocean currents in offshore basins in China,oxidation-reduction cycles of aqueous media and paleoclimate evolution in a high-frequency sequence framework.     

A note for the mechanism of high-frequency oscillation instability resulted from absorbing boundary conditions

In this paper the explanation of the mechanism of high-frequency oscillation instability resulted from absorbing boundary conditions is further improved. And we analytically prove the proposition that for one dimensional discrete model of elastic wave motion, the module of reflection factor will be greater than 1 in high frequency band when artificial wave velocity is greater than 1.5 times the ratio of discrete space step to discrete time step. Based on the proof, the frequency band in which instability occurs is discussed in detail, showing such high-frequency waves are meaningless for the numerical simulation of wave motion.