大冶干燥窑收尘系统改造及生产实践

本文介绍了大冶有色冶炼厂4#干燥窑尾气收尘改造和运行效果。前言大冶铜精矿干燥方式采用回转式干燥窑,热介质为粉煤燃烧产生高温空气,在干燥窑内,高温空气与铜精矿顺流接触,干燥过程中产生水蒸气及粉尘随尾气一起进入收尘系统处理后排空。该工艺于2003年10月建成投产,干燥精矿能力为80～100吨/小时,承担着铜精矿干燥的主要任务,原尾气收尘工艺为旋风收尘及水沫风收尘两级收尘工艺,但由于烟气量     

大冶干燥窑收尘系统改造实践

大冶铜精矿干燥方式采用回转式干燥窑,热介质为粉煤燃烧产生高温空气,在干燥窑内,高温空气与铜精矿顺流接触,干燥过程中产生水蒸气及粉尘随尾气一起进入收尘系统处理后排空。该工艺于2003年10月建成投产,干燥精矿能力为80-100吨／小时,承担着铜精矿干燥的主要任务,原尾气收尘工艺为旋风收尘及水沫风收尘两级收尘工艺,但由于烟气量大,烟气含水、含尘浓度较高以收尘系统效力低致使其尾气排放一直不达标。随着我国循环经济步伐加快和企业清洁生产的需要,迫切需要对干燥窑尾气收尘工艺进行改造。     

高温快速回火在节能热处理中的应用

介绍了淬火钢高温快速回火工艺,阐述了回火温度选定及回火时间的确定方法,分析了高温快速回火工艺的特点和适用范围。高温快速回火工艺可以显著缩短回火时间,降低能耗,提高生产率和企业经济效益。     

镁质捣打料在富氧侧吹工艺中的应用实践

对镁质捣打料的干燥、养护以及高温使用原理进行分析,介绍了镁质捣打料在烟台富氧侧吹工艺中的使用部位和填充方式。使用自制镁质捣打料是烟台富氧侧吹工艺的特点,其具有抗高温性能好、成本低、使用寿命长等优点。     

旋转闪蒸直燃供热式回转窑焙烧钼精矿的设备及工艺方法

一种新型旋转闪蒸直燃供热式回转窑焙烧钼精矿的设备及工艺方法,其具有钼精矿供料装置系统,回转窑装置系统,供热装置系统和烟尘处理回收装置系统;供料装置的旋转闪蒸干燥机,将物料快速干燥粉碎后送入回转窑内;供热装置由固体燃料高温热风炉产生的高温炽热火焰进入回转窑内,     

低热值燃料在钢包高温快速烘烤工艺中的应用

分析了高温快速烘烤工艺的特点和低热值燃料的燃烧特性,分析指出富氧燃烧是解决低热值燃料在高温快速烘烤工艺中应用问题的理想方法.     

铁氧体粉料制备工艺的新进展

综述了铁氧体粉料的新型制备方法的原理和主要工艺过程,包括自蔓延高温合成法、低温燃烧合成法、机械化学合成法、水热法、冷冻干燥法和超临界流体干燥法等。     

关于COREX工艺用煤的性能

针对混合煤在COREX气化炉中的主要行为,重点阐明了COREX工艺用煤的理化性能和高温性能必须满足一定的技术指标要求,以保证COREX工艺的正常生产。并结合COREX工艺用煤性能的要求,提出了对煤的进行筛分和干燥处理的工艺方案。     

微波在冶金材料加工中的应用现状

对低温分子筛的介电性能进行了研究,提出了微波干燥过程的高功率密度控制,研究了氧化锌烟在室温、高温、微波加热条件下的室温介电性能,采用响应面法优化了微波干燥和微波焙烧工艺参数。研究材料复介电常数对电磁场分布及温度场分布的影响以及微波加热腔中的材料受温度变化的影响等,对选择合适的微波加热工艺和发展微波加热具有重要的指导意义。     

新型矿热炉环保节能设计与分析

介绍了一种新型封闭式矿热炉的除尘净化系统和入炉料预热系统的工艺设计和节能原理.烟气在全封闭电炉中燃烧,利用高温烟气携带的热量对入炉料进行干燥、预热和预还原,达到节能目的.     

Comparison of MR pulse sequences in the detection of multiple sclerosis lesions

PURPOSE: To compare the sensitivity of conventional spin-echo, fast spin-echo, fast fluid-attenuated inversion recovery (FLAIR), and turbo gradient spin-echo MR sequences in the detection of multiple sclerosis lesions. METHODS: Conventional spin-echo, fast spin-echo, fast FLAIR, and turbo gradient spin-echo sequences were performed on a 1.0-T MR imager in seven patients with clinically definite multiple sclerosis. The images in each sequence were evaluated by two raters and consensus was reached by agreement. RESULTS: In comparing conventional spin-echo with fast spin-echo sequences, five lesions were seen only by conventional spin-echo and 63 were seen only by fast spin-echo; in comparing conventional spin-echo with fast FLAIR sequences, 18 lesions were seen only by conventional spin-echo and 109 only by fast FLAIR; in comparing conventional spin-echo with turbo gradient spin-echo sequences, 51 lesions were seen only by conventional spin-echo and seven only by turbo gradient spin-echo; in comparing fast spin-echo with fast FLAIR sequences, 45 lesions were seen only by fast spin-echo and 52 only by fast FLAIR. CONCLUSION: Fast spin-echo and fast FLAIR sequences improve the sensitivity of MR imaging in the detection of multiple sclerosis lesions with reduced acquisition time as compared with conventional spin-echo sequences. These sequences should therefore be considered for serial studies in patients with multiple sclerosis. The sensitivity of turbo gradient spin-echo was inferior to the other sequences, but its reduced acquisition time could make this technique the ideal choice for patients who cannot tolerate longer examination times.     

Posterior fast atrioventricular node pathways: implications for radiofrequency catheter ablation of atrioventricular node reentrant tachycardia

OBJECTIVES: This study sought to present evidence that fast atrioventricular (AV) node pathways with posterior exit sites may participate in typical AV node reentry. BACKGROUND: Catheter ablation of the slow AV node pathway in the posteroseptal right atrium is the preferred therapeutic approach in patients with AV node reentrant tachycardia. Despite the success achieved with this approach, electrophysiologic changes consistent with fast pathway ablation are occasionally observed. One potential explanation is the presence of an aberrant posterior fast pathway. METHODS: The location of fast and slow AV node pathways was determined by atrial activation mapping along the tricuspid valve annulus during tachycardia and was further confirmed by the effect of radiofrequency catheter ablation. RESULTS: Seven patients with AV node reentrant tachycardia had evidence of a posterior fast pathway near the coronary sinus os. Abolition of anterograde and retrograde fast pathway conduction followed radiofrequency ablation in the posteroseptal region in six patients. Consistent with fast pathway ablation, the AH interval increased from 70 +/- 24 to 195 +/- 35 ms (mean +/- SD), and tachycardia was no longer inducible. Selective slow pathway ablation was performed in one other patient with a posterior fast pathway. CONCLUSIONS: Functionally fast AV node pathways may be located in the posteroseptal right atrium, where slow pathway modification is performed. These data delineate the limitation of an anatomically guided slow pathway ablative approach and emphasize the importance of detailed mapping and localization of the retrograde fast pathway exit site before ablation. Failure to recognize the presence of posterior fast AV node pathways may account for sporadic examples of AV block, complicating posteroseptal ablation in patients with AV node reentry.     

大型热连轧线基于超快速冷却的新一代控轧控冷技术开发与应用

超快速冷却作为近年来热轧钢材控轧控冷技术领域最重要的技术突破，为热连轧产线产品的生产工艺进步提供了重要支撑。基于热连轧板带钢超快速冷却系统的开发与应用实践，在阐明高温运动钢板高强度均匀化冷却机理机制的基础上，重点介绍了超快冷系统在热连轧产线的工艺配置，以及采用超快冷工艺，在系列细晶钢、高钢级管线钢、热轧双相钢、低残余应力热轧板带钢等特色化产品领域的工艺开发及应用情况。基于超快冷系统冷却速度无级调控优势，开发了基于超快冷装备的层流冷却、加强型冷却、超快速冷却3种冷却模式及模型系统，进一步结合粗轧中间坯超快冷控温系统，构建了基于超快速冷却的热连轧线新一代控轧控冷多工序温度协同控制系统，相关技术应用取得良好效果。     

Fast K channels are more sensitive to riluzole than slow K channels in myelinated nerve fibre

The effects of 1-500 microM riluzole, a novel psychotropic agent, were studied on the nodal K current of isolated nerve fibres of the frog. When added to the external solution, the substance rapidly and reversibly inhibited slow, fast 1 and fast 2 K components of the tail K current. The concentrations of riluzole inducing half maximum reduction of slow, fast 1 and fast 2 K conductances were 413 microM, 24 microM and 21 microM respectively. It is concluded that the substance is about 20 times more effective in blocking fast than slow K channels.     

Characteristics of foveating and defoveating fast phases in latent nystagmus

PURPOSE: Under certain conditions, the fast phases of latent/manifest latent nystagmus (LMLN) can defoveate the target of interest instead of foveating it, as was thought to be their only function. LMLN fast phases in the waveforms from four subjects were studied with the goals of better understanding their characteristics and determining what triggers both foveating and defoveating fast phases. METHODS: Eye movement records were made using both the scleral search coil and infrared methods. Relationships of fast-phase sizes with slow-phase positions and velocities before and after fast phases were analyzed, as were relationships of saccade size with peak velocity and duration. RESULTS. The data showed that LMLN with defoveating fast phases occurred in the presence of higher slow-phase velocities. Also, larger saccade sizes corresponded to larger presaccadic and postsaccadic slow-phase velocities. The peak velocities and durations of LMLN fast phases were in the same ranges as normal saccades. CONCLUSIONS: Defoveating fast phases with decreasing-velocity slow phases may be the result of the addition of saccadic pulses to linear slow phases. Mechanisms are suggested to explain the switch from foveating to defoveating fast phases in LMLN.     

Differential effect of adenosine on anterograde and retrograde fast pathway conduction in patients with atrioventricular nodal reentrant tachycardia

INTRODUCTION: Several studies have shown that the fast pathway is more responsive to adenosine than the slow pathway in patients with AV nodal reentrant tachycardia. Little information is available regarding the effect of adenosine on anterograde and retrograde fast pathway conduction. METHODS AND RESULTS: The effects of adenosine on anterograde and retrograde fast pathway conduction were evaluated in 116 patients (mean age 47 +/- 16 years) with typical AV nodal reentrant tachycardia. Each patient received 12 mg of adenosine during ventricular pacing at a cycle length 20 msec longer than the fast pathway VA block cycle length and during sinus rhythm or atrial pacing at 20 msec longer than the fast pathway AV block cycle length. Anterograde block occurred in 98% of patients compared with retrograde fast pathway block in 62% of patients (P < 0.001). Unresponsiveness of the retrograde fast pathway to adenosine was associated with a shorter AV block cycle length (374 +/- 78 vs 333 +/- 74 msec, P < 0.01), a shorter VA block cycle length (383 +/- 121 vs 307 +/- 49 msec, P < 0.001), and a shorter VA interval during tachycardia (53 +/- 23 vs 41 +/- 17 msec, P < 0.01). CONCLUSION: Although anterograde fast pathway conduction is almost always blocked by 12 mg of adenosine, retrograde fast pathway conduction is not blocked by adenosine in 38% of patients with typical AV nodal reentrant tachycardia. This indicates that the anterograde and retrograde fast pathways may be anatomically and/or functionally distinct. Unresponsiveness of VA conduction to adenosine is not a reliable indicator of an accessory pathway.     

TRT快切系统保安功能探讨及改进

阐明TRT快切阀系统的作用、原理及特点，对3号TRT快切阀液压系统存在的问题进行分析，并对该液压系统进行改造，消除快切系统故障对TRT发电的影响，提高系统的可靠性，并为武钢所有TRT快切系统维护和改造奠定基础。     

Neuronal pathways for activation of inhibitory interneurons in pyriform cortex of the rabbit

The neuronal pathways responsible for the fast inhibitory postsynaptic potentials (IPSPs) elicited in principal cells in the pyriform cortex (PC) by volleys from the olfactory bulb (OB), the lateral olfactory tract (LOT), the anterior commissure (AC), and the deep-lying structures of the PC (DPC) were studied in the rabbit. The central latencies of the fast IPSPs (measured from the onset of the monosynaptic excitatory postsynaptic potential (EPSP) elicited by volleys through the LOT) ranged between 3.0 and 9.3 ms (5.5 +/- 1.3 (SD) ms; n = 54) in the case of OB shocks and between 4.5 and 6.5 ms (5.1 +/- 0.7 (SD) ms; n = 7) in the case of LOT shocks. The onset latencies of the fast IPSPs were between 2.5 and 11.8 ms (5.1 +/- 1.8 (SD) ms; n = 66) in the case of DPC shocks and between 3.5 and 10.1 ms (5.8 +/- 1.5 (SD) ms; n = 61) in the case of AC shocks. The conditioning OB or LOT shocks almost completely eliminated the LOT-evoked fast IPSP when the testing shock was applied at the peak period of the conditioning slow IPSP. The conditioning OB shocks also eliminated the initial part of the OB-evoked fast IPSP, leaving the later part of the fast IPSP almost unchanged. Thus, the onset latency of the OB-evoked fast IPSP was lengthened by 7.1 +/- 2.9 (SD) ms (n = 35) by the conditioning OB shock. The conditioning OB or DPC shocks left the peak amplitude of the DPC-evoked fast IPSP almost unaffected. Similarly, the conditioning OB or AC shocks left the peak amplitude of the AC-evoked fast IPSP almost unaffected. The conditioning OB, DPC, or AC shocks had only a slight influence on the onset latency of the DPC- or AC-evoked fast IPSPs. Rhythmical steps at intervals of 3-5 ms were observed in the rising phase of the OB-evoked fast IPSP. This was interpreted as a result of a repetitive impingement of interneuronal discharges on the impaled cells. Spatial facilitation was observed among the fast IPSPs evoked by volleys from the OB, DPC, and AC when shocks were applied at suitable intervals. A slight facilitation was also seen between the LOT-evoked fast IPSP and the DPC- or AC-evoked fast IPSP. These results were interpreted as a result of the convergence of excitatory synaptic inputs onto the presumed inhibitory interneurons from the four structures of the brain. A temporal facilitation of the fast IPSPs was observed when the OB, DPC, or AC shocks were applied repetitively at short intervals. This suggests a temporal facilitation of the spike discharges of the presumed inhibitory interneurons under similar conditions. From these results, criteria were determined for identifying the inhibitory interneurons.     

Voltage dependencies of the fast and slow gating modes of RIIA sodium channels

Rat brain IIA sodium channel alpha-subunits were expressed in Xenopus oocytes, and the sodium currents were measured by intracellular voltage clamping with large agarose-tipped electrodes and by excised membrane patch-clamp recording to separate and characterize the properties of the fast and slow channel gating modes. The currents showed biexponential inactivation properties with fast and slow phases that could be isolated as distinct gating modes through differences in their inactivation properties. At holding potentials more negative than -55 mV, fast mode currents inactivated within a few milliseconds of depolarization, and could be distinguished by their rapid recovery from inactivation. Single sodium channels in the fast mode opened early after depolarization and rarely showed re-openings. At holding potentials positive to -55 mV, fast mode currents were inactivated, revealing slow mode currents which had slower activation and inactivation kinetics and showed sustained single channel activity during depolarizing pulses. The steady-state voltage dependencies of fast and slow mode activation were very similar. In contrast, slow mode inactivation occurred at potentials 27 mV more positive than fast mode inactivation. The slow mode appears to be due to destabilization of a voltage-insensitive conformation of the channel. The fast gating process dominated at high current levels, perhaps due to alpha-subunit interactions.     

Upgrade Rolling Based on Ultra Fast Cooling Technology for C-Mn Steel

By measuring the expansion curves of a C-Mn steel at different cooling rates by using an MMS-300 thermo- mechanical simulator, continuous cooling transformation curves were obtained. The new process ＂ultra fast cooling＋ laminar cooling＂ was simulated and the effects of ultra fast cooling ending temperature on microstructure had also been investigated. The hot rolling experiment was done by adopting ＂high temperature rolling-[-forepart ultra fast cooling＂ technologies at laboratory scale. The results revealed that ultra fast cooling can delay the decrease of disloca- tion density and refine ferrite grains. Diversity control of the microstructure and phase transformation strengthening can be realized by changing the ultra fast cooling ending temperature. With the decrease of ultra fast cooling ending temperature, the strength and toughness increase, but plasticity does not decrease obviously. The new technique can improve the yield strength by over 50 MPa. Therefore, the upgrade of mechanical properties of C-Mn steel can be realized by using ＂high temperature rolling＋ ultra fast cooling＋laminar cooling＂ technique. Compared with ＂low temperature rolling with large deformation degree＂ technique, this new technology can decrease the roiling force and in- crease the production efficiency.