高输入功率因数的三相无源AC-DC变换器

对于采用三相不控整流桥作为前级的变换器，自然条件下其输入电流波形系数不高，使得输入功率因数委低，降低了电源的利用率。为此需要采用功率因数提高技术，其中无源PFC是一类重要的功率因数校正技术，在某些场合非常具有应用价值。本文介绍了几种三相无源AC-DC变换器的高功率因数方案，如采用LC滤波器、移相电抗器，谐振电抗器，移相变压器，相间变压器，相间电抗器等，在进行简单的工作原理描述后，给出了部分方案的MATLAB/SIMULINK仿真结果。     

单井注水吞吐在塔河油田的应用

在塔河油田开发生产过程中，个别油井在修井作业中出现先漏后喷的现象。在修井完成后，产量较前期有大幅增加。针对这类油井进行单井注水吞吐采油试验，研究发现钻遇定容封闭性油藏的油井适合单井注水吞吐开采。一方面利用油水重力分异，抬升油水界面，增加采出量；另一方面注水补充地层能量，恢复地层压力。该方法在塔河油田实际应用中，取得了较好的效果和较高的经济效益，也为提高定容封闭性油藏油井的采收率提供了一个较好的方法。     

基于CAN总线技术的果园气象监测网络节点的设计及实现

介绍了基于CAN总线的分布式果园气象监测系统,重点描述了单片机P87C591的特点及以它为控制核心构成的监测网络节点的实现。     

《石油沥青纸胎油毡》国家标准的修订

《石油沥青纸胎油毡》国家标准进行了第三次修订。本文介绍了修订的理由、修订的内容与依据，并与国内外同类产品标准进行了比较。     

Effects of Process Conditions on Desalting and Demetalization of Crude Oil

The efficiency of desalting for six crude oils was studied with a SY-1 dynamic simulation experimental installation. The demulsifier DC2 was examined for 1#, 2#, and 4# crude oil and DC4 was used for 3#, 5#, and 6# crude oil. The effects of temperature, electric field gradient, dosage of demulsifier, and washing water on the desalting efficiency of six crude oils were investigated. The results showed that at the optimization process condition after desalting, the desalting efficiency and the salt content of 1# crude oil reached 89.17% and 1.92 mg/L; that of 2# crude oil reached 85.08% and 1.04 mg/L; that of 3# crude oil reached 91.06% and 1.35 mg/L; that of 4# crude oil reached 81.67% and 1.51 mg/L; that of 5# crude oil reached 81.03% and 2.32 mg/L; and that of 6# crude oil reached 86.64% and 2.67 mg/L. Different crude oils have different metal contents. Three assistants, ammonium nitrate (TJ1), nitric acid (TJ3), and polyamine carboxylate (TJ4), were used to improve the efficiencies of desalting and demetalization of six crude oils. TJ4 was more efficient in removing calcium and iron for 1# and 2# crude oil. TJ1 was more efficient in desalting and demetalizing 5# crude oil. The efficiencies for removal of calcium, iron, nickel, and vanadium respectively reached 99.89%, 98.33%, 20.58%, and 43.02%. TJ3 has better efficiency desalting and demetalizing for 6# crude oil. With the concentration of TJ3 increasing from 0 to 80 mg/L, the desalting efficiency increases from 31.22% to 73.54%, and the iron removal efficiency increases from 56.0% to 74.05%.     

龙滩水电站左岸地下引水发电系统开挖支护

龙滩水电站左岸地下引水发电系统工程规模浩大,在0.5 km 2的范围内共布置有119条洞室。这些洞室在空间重叠,平竖相贯,形成庞大复杂的地下洞室群,且主要洞室尺寸庞大,其中地下厂房是目前世界上规模最大的地下厂房。龙滩水电站引水发电系统主要洞室的开挖支护方法,可供其他类似工程参考借鉴。     

BAS设计中的误区

文章结合实际经验,就BAS设计中存在的一些误区进行探讨,详细介绍在BAS设计中关于系统集成、DDC配置、设备控制及选择等方面容易出现的问题,并给出了解决问题的办法。     

集中供热优化节能自动控制系统的特点

国家十一五规划中明确指出:五年内节能20%。根据供热系统耗能比重和现状,集中供热的节能潜力非常大。安装优化节能集中供热控制系统,并依此提高运行管理水平,可取得事半功倍的节能效果。基于多年持久的调查、研究、试验、产品开发和实际应用,我们体会到:只有从集中供热的特点出发,才能使集中供热控制系统既可靠又简单、价低,达到既确保人体舒适又真正节能的目标。本文将对集中供热优化节能控制系统在热力学模型、计算机控制方案、节能效果、可靠性和软硬件选择原则等方面的特点进行介绍。     

A Single-Die 124 dB Stereo Audio Delta-Sigma ADC With 111 dB THD

This paper presents a highly power-efficient stereo delta-sigma ADC designed for high-precision applications, with measured inter-channel isolation over 130 dB. This design adopts a single-loop, fifth-order, 33 level analog modulator with positive and negative feedforward paths. An interpolated multilevel quantizer with unevenly weighted quantization levels replaces a conventional 5-bit flash type quantizer. These new techniques suppress signal dependent energy inside the delta-sigma loop, reduce internal channel coupling and power consumption. Manufactured in 0.35 mum double poly, three metal CMOS process, the single-die chip includes two analog modulators, on-chip bandgap reference circuit, decimation filter and serial interface circuits. The core die area is around 14.8 mm². The ADC achieves 124 dB dynamic range (A-weighted), -111 dB THD over 20 kHz bandwidth. Total power consumption is less than 330 mW.