Linear Plasma Sources for Large Area Film Deposition:A Brief Review

By utilization of different excitation power sources, linear plasma sources can be differentiated into DC, RF, VHF, microwave and dual frequency types. Through installing several linear plasma sources in parallel or adopting the so-called roll-to-roll （air-to-air） process, scale uniform linear plasma sources were realized and successfully applied to the deposition of large area uniform dielectric thin films, Furthermore, the magnetic field system can effectively reduce the recombination losses on the wall of the vacuum chamber and enhance the plasma density. Linear plasma sources with approximately one square meter deposition area with the plasma density of 1011 cm 3 have been developed, some of which have been used for the deposition of dielectric layers and large area plasma etching.

Stability Analysis on Power System with Large Power Source

In this paper, the stability problems of power systems with large power source are analyzed with viewpoint of energy balance. The phenomena are studied when the energy delivery are “blocked” by faults that occur on some key transmission lines of a large power source within a power system, on the transmission lines between the interconnected power systems, or on some key buses. The cases are based on a practical power system and its interconnected systems.

Large Units, Large Plants -Major Thermal Power Sources

China’s electric power industry as a basic industry, plays an important role in the longterm, sustained and healthy development of the whole national economy. China’s electric power industry attained great achievement in technology and economical results during the past eight years from 1987-1995. The total national installed generating capacity increased from 102.897 GW in 1987 to more than 200 GW in March, 1995.

Fired Models of Air-gun Source and Its Application

Air-gun is an important active seismic source.With the development of the theory about air-gun array,the technique for air-gun array design becomes mature and is widely used in petroleum exploration and geophysics.In order to adapt it to different research domains,different combination and fired models are needed.At the present time,there are two fired models of air-gun source,namely,reinforced initial pulse and reinforced first bubble pulse.The fired time,space between single guns,frequency and resolution of the two models are different.This comparison can supply the basis for its extensive application.

Major,trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province

The Mesoproterozoic(1.11 Ga)Umkondo large igneous province(LIP)in southern Africa and Antarctica was emplaced in<5 Myr and is dominated by low-Ti tholeiitic doleritic-gabbroic sills.It is of particular interest because it is the least studied LIP in southern Africa with both sublithospheric and lithospheric mantle sources proposed and it coincides with the early assembly of Rodinia,so it has importance in understanding the nature of magmatism and tectonics in and around the Kalahari craton during the Mesoproterozoic.In this study,we compiled a large database of existing(~750)and new(~100)major and trace element data for the Umkondo province,as well as 42 new Sr-Nd isotopic measurements,to provide constraints on its magma sources and geochemical evolution.Major element compositional variations in the low-Ti tholeiites are explained by low-pressure(1 kbar)three-phase fractional crystallisation(olivine,clinopyroxene and plagioclase)of a parent magma with~10 wt.%MgO in oxidising conditions(QFM+1).Inverse models show that the low-Ti tholeiitic magmas were derived as residual melts after the crystallization of 12%-33%olivine from primary komatiitic-basaltic magmas(up to~20 wt.%MgO)in equilibrium with mantle olivine(Fo90).Low Sm/Yb and TiO2/Yb-Nb/Yb indicate that the primary magmas were derived by 2%-20%shallow(40-50 km)partial melting of spinel lherzolite.High Sm/Yb is restricted to dyke swarms and may imply limited magma production from deeper(up to~70 km)garnet lherzolite-like sources.The low-Ti tholeiites of the Umkondo province are enriched in large ion lithophile elements(Rb-Sr-Cs-K)and depleted in high-field strength elements(Zr-Hf-Nb-Ta),indicating the involvement of crustal material and/or the subcontinental lithospheric mantle.This is supported by covariations in Th/Nb,Nb/Yb,Nb/La and Ce/Sm with generally negativeΔNb.Sr-Nd isotopes lend support to the notion that the Umkondo magmas were derived from depleted and/or enriched sublithospheric mantle sources and subsequently contaminated by enriched lithospheric material during emplacement(initial(at 1.11 Ga)^(87)Sr/^(86)Sr between 0.704820 and 0.737464 andεNd between-8.9 and+5.3).The Vredefort sills are significant as they display the most depleted Sr-Nd isotopic signatures(average initial ^(87)Sr/^(86)Sr of 0.705342 and averageεNd of 0.4)and are the least contaminated magma suite in the Umkondo province.Because of(i)the large volume of low-Ti magmas,(ii)evidence of a primary hot and MgO-rich(komatiitic)magma,and(iii)the short duration of magmatism,we suggest that the Umkondo province was formed by plume-induced melting of the sublithospheric mantle beneath the Kalahari craton in an extensional setting.This contrasts with previous suggestions that the heat source developed in response to the“thermal insulation”of the mantle beneath a thickened Kalahari craton in the absence of a mantle plume.There is further evidence from the elevated Zn/Fe that the sublithospheric mantle was lithologically heterogeneous and consisted of mixed peridotite and pyroxenite domains.There is a general lack of ultramafic cumulates in the low-Ti magma suite that may imply there was deeper ponding and storage of the primary magmas that fractionated large quantities of ultramafic rocks.There is also a paucity of high-Ti rocks in the Umkondo province that may reflect limited direct melting of the lithospheric mantle or that they are simply not as well-preserved in this province compared to the Karoo province.The similar trace element and Sr-Nd isotopic compositions of the Umkondo sills in southern Africa with the Borgmassivet sills in Antarctica support the concept that the Kalahari craton and Grunehogna terrane were adjoined at 1.11 Ga.The timing of the Umkondo province indicates there was localised lithospheric extension and upwelling asthenospheric mantle during a time of dominantly compressional tectonics on Earth at the end of the‘boring billion’.

Two highly efficient accumulation models of large gas fields in China

Based on reserve abundance,large gas fields in China can be divided into two types：type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,dominated by stratigraphic and lithologic gas reservoirs.The formation of these two types of large gas fields is related to the highly efficient accumulation of natural gas.The accumulation of high abundance gas fields is dependent on the rapid maturation of the source kitchen and huge residual pressure difference between the gas source kitchen and reservoir,which is the strong driving force for natural gas migration to traps.Whereas the accumulation of low abundance gas fields is more complicated,involving both volume flow charge during the burial stage and diffusion flow charge during the uplift stage,which results in large area accumulation and preservation of natural gas in low porosity and low permeability reservoirs.This conclusion should assist gas exploration in different geological settings.

“Exploring petroleum inside source kitchen”: Connotation and prospects of source rock oil and gas

Based on the transitional background of the global energy structure, exploration and development of unconventional oil and gas, and investigation of key basins, the unconventional oil and gas resources are divided into three types: source rock oil and gas, tight oil and gas, and retention and accumulated oil and gas. Source rock oil and gas resources are the global strategic supplies of oil and gas, the key resource components in the second 150-year life cycle of the future petroleum industry, and the primary targets for "exploring petroleum inside source kitchen". The geological connotation of source rock oil and gas was proposed, and the models of source rock oil and gas generation, expulsion and accumulation were built, and five source rock oil and gas generation sections were identified, which may determine the actual resource potential under available technical conditions. The formation mechanism of the "sweet sections" was investigated, that is, shale oil is mainly accumulated in the shale section that is close to the oil generation section and has higher porosity and permeability, while the "sweet sections" of coal-bed methane(CBM) and shale gas have self-contained source and reservoir and they are absorbed in coal seams or retained in the organic-rich black shale section, so evaluation and selection of good "sweet areas(sections)" is the key to "exploring petroleum inside source kitchen". Source rock oil and gas resources have a great potential and will experience a substantial growth for over ten world-class large "coexistence basins" of conventional-unconventional oil and gas in the future following North America, and also will be the primary contributor to oil stable development and the growth point of natural gas production in China, with expected contribution of 15% and 30% to oil and gas, respectively, in 2030. Challenges in source rock oil and gas development should be paid more attention to, theoretical innovation is strongly recommended, and a development pilot zone can be established to strengthen technology and promote national support. The source rock oil and gas geology is the latest progress of the "source control theory" at the stage of unconventional oil and gas. It will provide a new theoretical basis for the new journey of the upstream business in the post-industry age.

200-kg large explosive detonation facing 50-km thick crust beneath west Qinling,northeastern Tibetan plateau

It is difficult to acquire deep seismic reflection profiles on land using the standard oil-industry acquisition parameters. This is especially true over much of Tibetan plateau not only because of severe topography and rapid variation of both velocity and thickness of near-surface layer, but also strong attenuation of seismic wave through the thickest crust of the Earth. Large explosive sources had been successfully detonated in US, but its application in Tibetan plateau rarely has an example of good quality. Presented herein is the data of a 200-kg single shot we recorded in west Qinling, northeastern Tibetan plateau. The shot gather data with phenomenal signal-to-noise ratios illustrate the energy of the Prop phase. Although the observations are only limited to the northeastern Tibetan plateau and thus cannot comprise an exhaustive study, they nevertheless suggest that large explosions may be a useful exploration tool in Tibetan Plateau where standard seismic sources and profiling methods fail to produce adequate data of low crust.

Practices and Advances in Exploring the Subsurface Structure and Its Temporal Evolution with Repeatable Artificial Sources

The earth's structure may change with time under natural or anthropogenic loading.Monitoring the subtle changes of the subsurface structure with repeatable seismic sources such as repeating earthquakes,ambient seismic noise and artificial sources has become one of the hot topics in seismological research. These studies provide important clues in understanding the physical process of hazardous events such as earthquakes and volcanic eruptions. In this review we introduce the practices and advances in exploring and monitoring the subsurface structure with artificial seismic sources. This review is orgainzed as follows. Firstly,we describe the studies on the characteristics of different types of seismic source( especially the airgun source). Then the advances on data processing and mechanical understanding are depicted. At the end of this review,we reveal the prospects of future study of exploration and monitoring of the subsurface structure and its temporal variations using artificial sources.

An Experimental Study on Modulating the Large Volume Airgun Array Signals through Asynchronous Excitation

Large volume airgun arrays have been widely used in exploring and monitoring underground structures for nearly a decade.Nowadays,large volume airgun arrays adopt the synchronous excitation mode,and source characteristics are controlled by the source signal of a single airgun,which to some extent limits its application.In order to realize the asynchronous excitation of the airgun array,we developed a new firing system for the airgun array,and carried out a field experiment in the Binchuan Fixed Airgun Signal Transmission station to study the influences of the asynchronous excitation on the source signal.The experimental results show that:the newly developed airgun array firing system can ignite the airguns according to the setting time series with high precision.By designing the excitation time series,the asynchronous excitation can enhance the energy of airgun source signal at 3-5 Hz,and reduce the energy of pressure pulse wave at 6-18 Hz.The signal detection capability of the asynchronous excitation with time series mode is equivalent to the synchronous excitation.

RESEARCH ON TECHNOLOGY OF CONTROLLED SOURCE RADIO MAGNETOTELLURIC SYSTEM'S TRANSMITTER

The basic theory and principle of the artificial Controlled Source Radio Magneto Telluric(CSRMT) method is studied and a novel CSRMT transmitter in kH z frequency band is designed. The specific circuit and measured results of some key modules in transmitter are presented, and some outdoor experimental tests have been carried out, which shows that the completed prototype of transmitter can generate a continuous sine current with frequency up to 35.33 k Hz, peak-to-peak amplitude up to 40 A, and realize a reliable transmitting mode with multi-frequency and high-current. The transmitter has a wide operating band, large magnetic moment and high waveform fidelity, and can meet the requirements of shallow geological exploration with high-resolution.

Drift Control Technology Using Wire-Suspension for the Airgun Source Platform in Qilian Mountain

There are several key issues in dynamic monitoring of subsurface structures,such as signal-to-noise ratio( SNR),repeatability of seismic sources and accurate measurement of velocity. Using a large volume airgun source,we constructed a high-performance active system which mainly consists of airgun excitation and signal reception. In order to reduce the platform drift from the shot position,we put forward the platform drift control technique. Experimental results show that the technique can effectively solve the problem of platform drift from the set position under fluid impact after airgun excitation. The results of this study can be a reference for repeated airgun source detection at certain excitation sites.

Attenuation Characteristics of Earthquake Ground Motion for Large Volume Airgun

In order to further deepen the understanding of seismic wave propagation characteristics induced by the large volume airgun source,experimental data from multiple fixed excitation points in Fujian Province were used to obtain the equivalent single excitation high signal-to-noise ratio velocity and displacement records through linear stacking and simulation techniques.Then the peak displacements of different epicentral distances were used to calculate the equivalent magnitude of the airgun source excitation at different fixed excitation points so as to establish the attenuation relationship between equivalent magnitude,epicenter distance and velocity peak.Our results show that:①Within 270 km of epicentral distance,for the large-volume airgun’s single shot,the peak velocity range is about 700-4 nm/s,and the peak displacement range is about 200.0-0.2 nm;②The equivalent magnitude of the P-wave from the airgun source with a total capacity of 8,000 in 3 is 0.181-0.760,and the equivalent magnitude of the S-wave is 0.294-0.832.By contrast,the equivalent magnitude of the P-wave from the airgun source with a total capacity of 12,000 in 3 is 0.533-0.896,and the equivalent magnitude of the S-wave is 0.611-0.946.The S-wave energy is greater than the P-wave energy,and the excitation efficiency varies greatly with different excitation environment;③The peak velocity increases with the equivalent magnitude,and decreases with the epicentral distance.The vertical component of the P-wave peak velocity is the largest among those three components,while the S-wave has the smallest vertical component and similar horizontal components.Hence,our research can provide an important basis for the quantitative judgment of the seismic wave propagation distance using the airgun and the design of the observation system in deep exploration or monitoring with airgun.

大口径辅助阳极型辉光放电溅射源的设计与研究

辉光放电原子发射光谱分析技术可对金属样品表面进行沿深度方向的逐层分析与表征,具有溅射速率快、分析效率高、可大面积溅射的优点。另外,辉光放电等离子体能量较低,材料逐层溅射激发过程中不易引起材料本身组织结构的变化,能够实现沿样品深度方向逐层剥蚀制样。将辉光放电溅射源与扫描电镜、光谱分析检测仪器等联用,可作为金属材料高通量定量表征的有效手段。为了高通量地获取材料表面的成分分布信息,需要对材料表面在多尺寸、大面积溅射条件下进行辉光放电等离子体溅射。因此在传统辉光溅射源的基础上,改进了阳极筒结构,设计了4种直径为cm级的(15、20、30和40 mm)大口径阳极筒,并对其进行COMSOL数值模拟仿真和实际溅射效果研究。大尺寸溅射面可获得材料表面更为丰富的信息,但在相同溅射条件下,阳极口径增大也带来溅射速率下降、溅射面中心区域离子化率降低、影响溅射均匀性和坑型平整度等问题。为解决这些问题,设计了可应用于大口径直流辉光放电溅射源的辅助阳极结构,通过改变放电空间的电场分布情况调控等离子体分布,增强了阳极中心区域离子化率。详细阐述了辅助阳极结构的设计原理,并对传统阳极和辅助阳极进行了数值模拟仿真研究和实际溅射效果对比实验。结果表明增设辅助阳极对大口径溅射源溅射速率的提升效果明显,对阳极口径30 mm溅射源的溅射速率提升33%~48%,对阳极口径40 mm溅射源的溅射速率提升34%~57%。采用大口径辅助阳极型溅射源对紫铜样品进行了溅射激发,并用光学相干断层扫描仪(OCT)测试了溅射坑形貌,结果表明增设辅助阳极可有效改善溅射均匀性和坑型平整度。

大语言模型驱动的开源情报认知

随着开源情报在军事领域的广泛应用,对相关情报的认知和分析需求日益增长。然而,当前研究人员所使用的大语言模型存在严重的幻觉现象,导致其生成的信息不可靠,无法直接用于军事开源情报的认知任务。为了解决这一问题,通过网上收集构建一个包含约10万条对话记录的军事开源情报数据集;利用LLaMA-13B模型作为基座,通过微调训练得到一个新的模型——ChatBIT,专门针对军事领域的对话和问答任务进行优化。对比分析ChatBIT模型与Vicuna-13B模型在军事知识问答方面的能力,通过一系列标准化的指标评估,包括Bleu值、Rouge-1、Rouge-2和Rouge-L,可知ChatBIT在所有指标上均优于Vicuna-13B。具体来说,相比Vicuna-13B,ChatBIT的Bleu值高2.3909,Rouge-1值高3.2079,Rouge-2值高2.2562,Rouge-L值高1.5939。结果表明,ChatBIT模型在处理军事领域的对话和问答任务时,能够提供更准确、更可靠的信息。

模块化高压大容量DC/DC变换器综述

随着新能源发电占比增加和电网规模的不断扩大,直流输电系统的容量不断提升,含有不同电压等级的直流电网是未来发展的必然趋势。在此背景下,DC/DC变换器作为直流电网关键设备,在多电压等级互联场景中发挥着重要作用。文中首先对已有的模块化高压大容量DC/DC变换器进行归纳、分类和比较,然后阐述了目前模块化高压大容量DC/DC变换器的拓扑结构、工作原理与特点,并针对其特点提出了不同变换器的适用场景,最后对未来的研究方向提出了建议。

大定源回线装置瞬变电磁法在煤矿采空区探测中的应用

该文通过研究大定源回线装置瞬变电磁法在煤矿采空区探测中的应用,旨在提高煤矿采空区探测的效率和准确性。深入探讨大定源回线装置瞬变电磁法的原理和工作机制。在此基础上,设计并实施适用于煤矿采空区的探测方案,并通过试验进行验证。结果表明,大定源回线装置瞬变电磁法在煤矿采空区探测中取得显著的效果。大定源回线装置瞬变电磁法具有高效、准确、可靠的特点,能够快速识别采空区位置,为后续生产建设提供保障,同时也为其他煤矿采空区勘察提供参考。

周期性脉动源对风力机功率的影响

针对WindPACT1.5 MW机组,通过大涡模拟探究风轮5°仰角时周期性脉动源(仰角、塔影效应、偏航、风剪切)对风力机总功率的影响,并结合逆叶素动量理论,进一步分析功率与升力系数之间的联系。结果表明,仰角、塔影效应加仰角与偏航加仰角均使得风力机总功率产生“3P”的波动规律,而风剪切加仰角使得总功率产生“锯齿状”的高频率波动规律,其中偏航是总功率损失的主要因素,塔影效应是功率波动的主要因素,且发现升力系数波动规律与功率单周期内的波动规律相似。

大型地埋管群地源热泵三维传热-渗流耦合模拟

为确定地下水渗流对大尺度、多分支埋管集群地源热泵系统换热区温度场和换热特性的影响,基于上海天文馆880个地埋管地源热泵场地,建立考虑地下水渗流和地质分层的三维传热-渗流耦合模型,并利用现场热响应试验对模型进行验证。结果表明:渗流作用引起管群内和支管群之间沿地下水流动方向发生温度干扰,89.5~120.3 m埋深范围内的温度干扰现象相对明显;地下水渗流有利于提高管群的换热总量,缩小夏季和冬季工况的换热量差距;换热量增加百分比随水力梯度的增加而增大,两者呈对数函数关系,当水力梯度大于0.005时,换热量增加百分比趋于平稳。

某大科学装置项目工艺冷却水系统设计

介绍了某在建大科学装置项目的工艺冷却水系统设计,包括服务对象、系统形式、系统组成、水温控制策略、流量控制策略等方面的内容。简述了热回收型水源热泵在工艺冷却水系统中的应用方案,并对工艺冷却水系统设计后续可开展的工作和研究提出了3个方向。