应用于PWM转换器的高性能误差放大器

基于整个环路稳定性的分析,提出一种高性能误差放大器,该电路与芯片外围的反激式应用电路一起完成负反馈调节.基于700V BCD工艺,对该电路的应用芯片进行仿真和流片.测试结果表明,该电路产生的动态阻抗为18Ω,PWM增益为-25.3%/mA,满足工程应用要求,实现系统稳定输出.     

Investigation on the swirlmeter performance in low pressure wet gas flow

Wet gas flow is a subset of gas-liquid two-phase flow, and the swirlmeter has been used in wet gas flow metering more and more recently. The swirlmeter performance in low pressure wet gas flow was investigated. It is found that the entrained liquid present in a gas stream tends to induce a negative bias in the gas flow rate reading of swirlmeter comparing with equal gas flow rate. When the Lockhart-Martinelli parameter X, which is closely related to the liquid fraction, is bigger than a threshold value, the swirlmeter will not properly work due to the disappearing of vortex precession. It is also found that the liquid-induced gas flow rate reading errors of swirlmeter are dependent on X and the gas densiometric Froude number Fr_g. A correlation for swirlmeter in low pressure wet gas flow is proposed, and it corrects the liquid-induced gas flow rate errors to an accepted accuracy under the tested conditions. It implies that the swirlmeter with the proposed correlation and the known liquid fraction may be used to meter the gas flow rate in wet gas applications with a relatively low liquid fraction.     

Hilbert-shaped complementary single split ring resonator and low-pass filter with ultra-wide stopband, excellent selectivity and low insertion-loss

A novel Hilbert-shaped complementary single split ring resonator (H-CSSRR) with an alterative split gap was initially presented and studied. Transmission characteristics of several CSSRR cells were assessed by full-wave electromagnetic (EM) simulation and analyzed by electrical simulation (equivalent circuit model). Miniaturization mechanism as well as effective EM parameters retrieval is also involved. Comparing to conventional CSSRR, proposed H-CSSRR was demonstrated with a merit of lower primary transmission zero realized by negative effective permittivity and multi-resonance behavior attributing to self-similarity of Hilbert geometry. For application, a tunable assembled low-pass filter (LPF) by periodically loading H-CSSRR cells and open stubs is designed, fabricated and measured. Measurement results indicate that the designed LPF has many good performances such as relative low insertion loss (maximum 0.59 dB) in passband, ultra-wide stop-band characterized by 20 dB insertion loss (from 2.45 to 25 GHz) as well as steep rejection with sharp transition band (2.15–2.45 GHz) out of band. Excellent property and consistent numerical and experimental results of the developed LPF have confirmed the effectiveness of this design concept.     

地质块段法在固体矿产资源储量估算的应用探讨

地质块段法是现在固体矿产勘查工作中最常用的方法。地质块段法一般是用块段的平均倾角和块段投影面积换算得真面积,用块段真面积和块段矿体平均真厚度计算矿体的体积,再与矿石体重相乘而得矿石量。块段的平均倾角是统计得来的,在矿体产状变化极大,平均倾角误差大,甚至无法统计的情况下,会导致资源储量估算误差很大。建议用块段平均铅重厚度与投影面积计算矿体体积,这样估算的资源储量误差相对更可靠。     

关于加强我国矿产资源储备工作的思考

本文分析了矿产资源储备面临的国内外形势及问题,提出了加强我国矿产资源储备的对策和建议。研究认为:全球矿产资源安全形势日趋复杂,冷战后降至低点的矿产资源储备再度受到西方国家关注;未来10年我国矿产资源供需形势将出现分异,但总体安全状况仍不容乐观。建议建立以矿产品储备为主、产能和产地储备为辅的储备体系,完善储备机制体制,扩大储备品种和规模,着重加强国防军工和高技术产业所需矿产的储备。     

油气预测储量区块升级评价方法

以油气预测储量区块为研究对象,以优选区块升级为目的,提出了升级性评价方法、升级率评价方法、经济评价方法及综合评价方法。研究提出:升级难易程度指数值用于升级性定量评价;升级概率值用于升级率评价;贴现现金流法计算的储量价值用于经济评价。综合评价则利用升级难易程度指数值、升级概率值、经济价值"一维排队,三维优选"。利用综合评价值,将预测储量区块分为可升级并获得大中规模储量区块、可升级并获得中小规模储量区块、需要评价研究升级的储量区块、暂不升级的储量区块4类,便于勘探决策。     

我国青藏高原矿产地储备战略思考

做好矿产地储备工作,有利于保持我国优势矿产资源的国际优势地位、增强话语权,保障短缺大宗矿产资源的安全供应,促进矿产资源的代际合理分配和永续利用。在分析青藏高原地质工作相关情况的基础上,从维护国家经济安全、推进生态文明建设、平衡资源代际分配、增强国际市场话语权、化解产能过剩等方面论述青藏高原矿产地储备的必要性。同时,着力从矿种、区位、勘查程度和工作思路等方面展开对青藏高原矿产地储备的思考。最后针对性提出设立矿产地储备专项资金、建立矿产地储备管理体制和制定矿产地储备专项规划等对策建议。     

歪头山铁矿采场新水平准备工作的合理性探析

结合歪头山铁矿采场生产现状及采场技术条件,对采场将计划进行的新水平准备工作—56m 水平掘沟工程的合理性进行了探讨和分析,提出了否定性的观点并予以阐述。     

电磁搅拌对板坯质量及中厚板力学性能的影响

分析了板坯连铸机电磁搅拌对板坯质量及中厚板力学性能的影响.从铸坯低倍检测可以看出电磁搅拌使用后铸坯内部中心偏析明显改善,中间裂纹得以消除;采用电磁搅拌辊安装在一段末和二段末的方式,负偏析带宽度由原来的10 mm减小到了5 mm左右,正、负偏析带上的成分与熔炼成分相差较小.从轧制钢板结果表明:负偏析带在轧制过程中具有遗传...