动态电压恢复器的最小能量补偿策略改进

通过对动态电压恢复器(DVR)进行电压跌落补偿策略的研究和最小能量补偿策略分析,发现改进DVR接人系统的拓扑结构,即在负荷端并联一个可调电抗器,电压跌落补偿时投入使用,负载功率因数越低,DVR补偿时消耗的能量越小,越容易实现纯无功补偿.提出暂时降低负荷功率因数来保证DVR在补偿时消耗能量最小的补偿策略.仿真结果表明,对结构改进是有效的,另外还可延长补偿时间.     

动态电压调节装置(DVR)在制氧机上的应用

介绍了电压跌落对钢铁企业生产的影响,对动态电压补偿器的工作原理和过程做了介绍,并通过应用实例说明了动态电压补偿器的使用效果。     

宝钢供配电系统电压跌落相关问题探讨

电能质量的优劣对钢铁企业的稳定运行具有重要意义。作为一个较为突出的电能质量问题,电压跌落问题正日益被关注。自2005年以来,宝钢已经发生过多起因外部电网故障而导致电压跌落事故。从宝钢实际出发,对电压跌落相关问题进行了分析和讨论,并且提出一些预防电压跌落的控制措施。     

静止型动态无功补偿装置在工业电网上的应用

SVC补偿技术是当前无功补偿领域中最具活力和发展前途的一项技术，已日益受到关注并得到广泛应用。随着电力电子技术及计算机控制技术的发展，各种新型的自动、快速无功补偿装置相继出现，也大大推动了SVC补偿技术的进步。本文对由可控硅供电的大型轧机(及类似负荷)造成的冲击电压波动、谐波、电压闪变等作了简要分析：说明了传统无功补偿方法存在的问题；着重阐述SVC补偿装置的特点、类型、功能，以及工程设计及应用中应注意的一些问题。     

无功电压调整在武钢电网经济调度中应用

研究了武钢电网经济调度中的无功电压调整问题,从有载变压器档位调整、无功补偿装置调节、利用自发电机组进相运行调整几个方法提出了无功电压的调整思路。     

超高功率电弧炉对电网不利影响的抑制分析

研究了超高功率电弧炉对电网的影响以及抑制方法,分析了电弧炉的功率因数低、电压闪变和波动、负序电压等不利影响,并探讨了静止型无功补偿装置在电弧炉补偿中的应用。针对电压波动值和补偿容量的计算,提供了相应的计算公式。在电弧炉参数、供电设备和电源改进方面,讨论了预热废钢料、破碎工艺和喷吹辅助燃料等措施。此外,介绍了配电用静止补偿器和有源滤波器的工作原理和优势。强调了电网电能质量管理的重要性,并展望了未来的发展趋势。研究结果对电网稳定性和电弧炉运行具有重要的参考价值。     

电能质量电压暂降问题及应对方案

介绍了电压暂降产生的原因和危害及电压暂降相关的国际标准,叙述了电压补偿型装置、失压脱扣装置和高压供电安全防护墙等电压暂降应对方案,指出电压暂降问题需从供电侧和用电侧同时考虑、分别治理,依据标准,针对不同用户和设备特性,采取减少或消除电压暂降冲击的手段,以达到满意的动态电能质量需求.     

电压比较型微机电子秤及其应用

介绍了电压比较型电子秤的组成以及测量放大器的工作原理和计量方法，对称重传感器输入电压进行自动补偿，以及用２片普通的ＤＡＣ１２３０并联构成高分辨率Ａ／Ｄ转向器等。该装置在湘钢配比控制系统中已稳定了２年，配料速度为５ｔ／ｈ，累积误差小于０．３％。     

企业配电网电压跌落原因分析及控制策略

文章以一起电网短路故障引起电压跌落事故为例,分别从供电运行方式、继电保护整定、中低压电网抗晃电能力等方面展开论述,分析电压跌落引起用电设备跳车的原因,并提出相应的控制措施以减少事故带来的经济损失。     

矿石还原电炉二次电压选择及其制约因素浅析

讨论了矿热电炉二次电压的制约因素,包括变压器容量、设备电抗、设备电阻、功率因数、电效率与二次电压的关系、物料性质及炉料电阻对二次电压的影响。对于不同的铁合金冶炼品种,其二次电压的选择也不相同。加装无功补偿电容装置,可有效地提高电炉系统的功率因数。确定了合理的电炉工艺参数,最佳二次电压值的选择,可保证电炉获得较高的熔池功率,取得良好的指标。     

Infants' mother–stranger discrimination at 3 months as a predictor of cognitive development at 3 and 5 years.

Utilized differential vocal response (DVR) to an interactive mother vs an interactive stranger to classify 12 3-mo-old male firstborn infants into either a high or low DVR group. The high DVR group responded significantly above base rate to stimulation by the mother and significantly below base rate to stimulation by the stranger, whereas the low DVR group responded at base rate to both mother and stranger. The high DVR group subsequently performed significantly better on both the Stanford-Binet Intelligence Scale at age 3 yrs and the Illinois Test of Psycholinguistic Abilities at 5 yrs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of ECG variables of dispersion of ventricular repolarization with direct myocardial repolarization measurements in the human heart

INTRODUCTION: QT dispersion (QTD) from the 12-lead ECG has been widely adopted as a noninvasive index of dispersion of ventricular repolarization (DVR). QTD, however, has never been validated by direct comparison with myocardial DVR in the human heart. METHODS AND RESULTS: Monophasic action potential (MAP) recordings obtained in an earlier study were retrospectively matched with 12-lead ECGs available from within 24 hours of the invasive procedure. MAPs were available from an average of 8+/-3 left endocardial sites in 4 patients with left ventricular hypertrophy (LVH) and 7 patients with normal ECGs, and 6+/-2 epicardial sites in 3 patients of each group during normal ventricular activation. Local repolarization time (RT) was determined as MAP duration at 90% repolarization plus the local activation time. Dispersion of RT was calculated as the difference between the earliest and latest RT. ECGs were digitized and analyzed with recently described interactive QTD analysis software. In addition to standard QTD (defined as QTmax-QTmin), all currently proposed ECG dispersion variables were compared and correlated with the invasive measurements of DVR. QTD exhibited a reasonable correlation with dispersion of RT (R = 0.67; P < 0.01). Several other variables designed to measure DVR exhibited a similar, but not better, correlation. Among them, the QT peak/QT end ratio in V3 (R = -0.72; P < 0.01) and averaged over all analyzable leads (R = -0.59; P < 0.01) exhibited a good correlation with dispersion of RT, which was further improved when endocardial measurements were considered alone. T area measures did not correlate with dispersion of RT, but discriminated LVH. CONCLUSION: DVR can be assessed by means of a 12-lead surface ECG. Several of the variables under study exhibit a similar accuracy in determination of true myocardial dispersion of repolarization. Variables involving the terminal part of repolarization, such as the QT peak/QT ratio, even from a single lead, may add to the determination of DVR from the human heart.     

静态无功补偿装置（SVC）在100t电炉的应用

SVC可以显著降低电弧炉变压器一次侧电压衰减，提高二次侧电压和变压器输出功率，有利于提高电炉产能，但同时也造成电炉冶炼电耗的增加。通过控制入炉功率或改善泡沫渣状况可以使冶炼电耗恢复到正常水平。     

Age differences in a sample of state vocational rehabilitation clients with traumatic brain injury.

Objective: To examine the relations among age, neuropsychological functioning, and vocational rehabilitation following traumatic brain injury (TBI). Study Design and Participants: Prospective study of 78 adults (18-57 years) who qualified for services with the Missouri Division of Vocational Rehabilitation (DVR), based on a history of TBI followed from enrollment to case closure. Group differences based on age were examined for neuropsychological and vocational outcome with multivariate analysis of variance and nonparametric methods. Main Outcome Measures: Neuropsychological test data and DVR data regarding vocational placement. Results: Age-related differences were present for a measure of mental flexibility, isolated demographic characteristics, and 1 DVR service category. Contrary to hypotheses, there were no age-related differences in vocational outcome. Conclusions: In contrast to hospital-based samples, age does not appear to be a negative indicator for individuals admitted to a state DVR program. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

35kV系统限流电抗器在变电站中的研究与应用

电抗器是用来限制电路中的短路电流和提高系统的残压,利用其电感特性。降低短路电流对电网的冲击,保护电网的稳定性。同时电抗器会在线路中损耗一部分电压和电能。老式的电抗器,由于压降较大,为了保证用户端的电压等级达标,就必须增加电源端的电压等级。当电源端的电压等级提高就加速了输电设备的绝缘老化,增加了故障发生率,所以需探讨限流电抗器在变电站中的安全应用。     

某特钢工程svc装置的设计与应用

SVC装置能有效解决交流电弧炉在冶炼过程中,引起供电电网的电压波动和闪变,三相电压不平衡,并向电网注入谐波电流。通过计算某特钢工程电炉供电系统的阻抗,从而确定电炉的最大无功冲击和无功变动量;计算提高功率因数所需的无功补偿量,对SVC装置进行设计。     

软启动装置在高压电动机中的运用

大容量高压电动机直接启动时,其启动电流较大,所需要的供电容量要大。采取软启动装置启动大容量高压电动机时,可减小高压电机的启动电流,提高供电系统的稳定性。软启动装置有多种类型,江西铜业集团公司硫酸德兴铜矿硫酸厂800kW的高压电机使用的是热变电阻软启动装置,运行半年多,达到了减少启动电流的目的,提高了供电系统的稳定性,运行效果良好。     

Dopamine transporter imaging with fluorine-18-FPCIT and PET

Fluorinated N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane (FPCIT) has been synthesized as a dopamine transporter ligand for PET studies. We evaluated the regional brain uptake and the plasma metabolism of [18F]-FPCIT. METHODS: PET studies were conducted on 7 normal subjects and on 10 patients with Parkinson's disease. After the [18F]-FPCIT injection (4.4+/-1.8 mCi), dynamic scans were acquired over 100 min. Plasma metabolite analysis was performed using high-performance liquid chromatography (HPLC). RESULTS: Plasma HPLC revealed two peaks corresponding to unmetabolized [18F]-FPCIT and a polar metabolite. The fraction of the parent compound decreased rapidly to 25% at 25 min. Fluorine-18-FPCIT showed a striatum-to-occipital ratio (SOR) of 3.5 at 90 min postinjection. The ratio of striatal-to-occipital distribution volume (DVR) was calculated directly by using a mean tissue-to-plasma efflux constant for occipital cortex obtained in 10 subjects (ki=0.037 min(-1)). DVR measures determined with and without plasma input function were correlated (r=0.98, p < 0.0001). In normal subjects, a significant age-related decline of DVR was observed both for caudate and putamen, corresponding to a 7.7% and 6.4% decline per decade, respectively (r > 0.85, p < 0.01). Both DVR and SOR correctly classified early-stage Parkinson's disease patients with comparable accuracy (p < 0.0001). Age-corrected DVR values correlated negatively with the Uniform Parkinson's Disease Rating Scale composite motor ratings (r=0.66, p < 0.05). CONCLUSION: The tracer characteristics are compatible with a high-affinity, reversible ligand. FPCIT/PET demonstrated age-related decline in dopamine transporter binding in normal subjects as well as significant reductions in patients with idiopathic Parkinson's disease, which correlates with the disease severity.     

铝电解槽节能潜力分析与应用实践

铝电解槽的电能消耗量与平均电压和电流效率两个因素有关,降低槽电压或者提高电流效率,可降低铝电解槽直流电耗。通过系统测试系列电解槽电压平衡、能量平衡、电流效率,深入挖掘分析,提出了节能降耗技术措施。通过2台试验槽工业试验表明,试验槽平均电压3.819 V,电流效率92.89%,吨铝直流电耗12 251 kWh。与系列电解槽相比,平均电压降低99 mV,电流效率提高1个百分点,吨铝直流电耗降低455 kWh,节能效果显著。     

差动保护原理在66kV变电所供电系统中的应用

结合总降压变电所的实际情况，介绍差动保护原理在我公司高压供电系统中应用的三种方式，并分别对。其在各自保护范围内出现的故障进行分析。运行结果表明，该套装置能够保证供电系统安全可靠运行。