八钢高线生产φ12.5mm82B工艺分析

针对82B热轧盘条的特点,通过控温、控冷工艺分析,梳理影响其产品质量和性能的主要影响因素,通过生产实践对控温、控制冷却工艺优化,生产出合格产品;同时,为提高和改进φ12.5mm82B的质量,减少产品使用时偶发的中心网碳等异常组织缺陷问题,据现有工艺设备配置状况提出了改进建议,以确保82B产品质量和性能的稳定。     

Notes on early photography in Albania

Abstract

The manner in which the photographic invention interacted with various societies and national temperaments is undoubtedly one of the most interesting aspects of this field. Very little has been published about the arrival and development of photography in Albania. This article is based in part on conversations with the Albanian photographers Gegë Marubi, Piro Milkani and others, in the autumn of 1980¹.     

Implementing incentive compatible menus of contracts to regulate electricity distribution investments

Investment regulation constitutes one of the major difficulties in regulating monopolistic activities such as electricity distribution. Information asymmetries and uncertainties over technology and demand especially hamper the evaluation of the efficiency of network investments. In this context, ex-ante regulatory schemes with ex-post corrections such as profit sharing contracts can be particularly useful. Moreover, menu regulation could encourage distribution firms to provide regulators with more accurate information. However, such a mechanism is rarely applied in electricity distribution. In order to facilitate its diffusion, this paper provides clear guidelines to construct incentive compatible menus of profit-sharing contracts and discusses its possible implementation in Spain.     

控轧控冷工艺对82B盘条时效性能的影响

重点研究了终轧温度、冷却速度以及吐丝温度对82B盘条时效性能的影响，旨在得到缩短82B盘条生产时效时间的热轧工艺。     

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 φ12.5mm 82MnA 高碳钢热轧盘条拉拔过程中发生断裂，为了找到盘条断裂原因,对断裂盘条试样，采用体视显微镜、光学显微镜、扫描电镜及X射线能谱仪等手段对其表面缺陷、金相组织、非金属夹杂物进行了分析和测试。结果表明：82MnA钢纯净度、盘条表面缺陷、心部成分偏析、心部组织异常和DS类夹杂物最终导致φ12.5mm 82MnA 高碳钢盘条在拉拔过程中断裂。     

Concentration effects in mesoscopic simulation of coarsening

The self-organization of particles in a two-phase system in the coexistence region through a diffusive mechanism is known as Ostwald ripening. A mesoscopic model derived from the spin exchange Ising model is used here in a computational study of Ostwald ripening. The typical cluster size is observed to grow like Lifshitz–Slyozov growth law over an early range of times with faster growth at later times. The effect of changing the concentration of particles on the morphological evolution of the system is also discussed.     

Reducing asymmetric information in insurance markets: Cars with black boxes

Monitoring and recording driving behavior has become technologically feasible recently which allows inference of drivers’ risk types. We examine the effects of such technologies in automobile insurance markets with adverse selection for both perfect competition and monopoly. Specifically, we assume that insurers can offer a contract with access to recorded information ex post, i.e., after an accident, in addition to the usual second-best contracts. We find that this leads to a Pareto-improvement of social welfare except when high risks initially received an information rent. Regulation can be used to establish Pareto-improvement also in these cases. Explicit consideration of privacy concerns of insurees does not alter our positive welfare results.     

家庭天然气管道泄露监测系统的设计

这里设计了一种结构简单且具有较强实用意义的家庭天然气管道泄漏检测系统。该系统基于AT82S52单片机收集信号,并针对天然气的特征进行各类气敏传感器的对比选择。使用MQ?2型半导体气敏传感器,用C语言进行程序编程,最终制作出的监测系统实物可以通过按键设定报警浓度上限。当空气中天然气的浓度超过预定值时会出现声光双重报警,且制作成本较低。     

大规格82B高碳钢盘条难酸洗原因研究

针对酒钢生产的大规格φ10.0~φ16.0 mm 82B盘条表面磷化膜在拉丝工艺中易脱落,氧化层中难酸洗的Fe₃O₄含量相对较高,拉拔困难的问题,选用酒钢和A钢厂生产的φ12.5 mm规格82B盘条,用SEM观察盘条表面氧化层厚度和结构组成,用EDS分析氧化层各层元素的分布,用XRD检测氧化层物相的种类和比例。结果发现,酒钢生产的盘条表面粗糙度大,氧化层在盘条表面呈犬牙交替的结合方式;Fe₃O₄的质量分数较A钢厂盘条高39.1%,含CrSi₂层也较致密。为此,对生产工艺提出了优化措施,通过降低吐丝温度和提高冷速,来提高易酸洗相FeO的比例,减少在共析反应最激烈的450~550 ℃温度区间的停留时间,从而减少了难酸洗相Fe₃O₄的含量,改善了盘条的酸洗性能。     

Experimental study and detailed kinetic modeling of the effect of exhaust gas on fuel combustion: mutual sensitization of the oxidation of nitric oxide and methane over extended temperature and pressure ranges

New experimental results were obtained for the mutual sensitization of the oxidation of NO and methane in a fused silica jet-stirred reactor operating at 1-10 atm, over the temperature range 800-1150 K. Probe sampling followed by on-line FTIR analyses and off-line GC-TCD/FID analyses allowed the measurement of concentration profiles for the reactants, stable intermediates, and final products. Detailed chemical kinetic modeling of the experiments was performed. An overall reasonable agreement between the present data and modeling was obtained, whereas previously published models failed to properly represent these new data. According to the proposed model, the mutual sensitization of the oxidation of methane and NO proceeds through the NO to NO₂ conversion by HO₂ and CH₃O₂. The modeling showed that at 1-10 atm, the conversion of NO to NO₂ by CH₃O₂, is more important at low temperatures (800 K) than at higher temperatures (850-900 K), where the reaction of NO with HO₂ dominates the production of NO₂. The NO to NO₂ conversion is enhanced by the production of HO₂ and CH₃O₂ radicals from the oxidation of the fuel. The production of OH resulting from the oxidation of NO promotes the oxidation of the fuel: NO + HO₂ ? OH + NO₂ is followed by OH + CH₄ ? CH₃. At low temperature, the reaction further proceeds via CH₃ + O₂ ? CH₃O₂, CH₃O₂ + NO ? CH₃O + NO₂. At higher temperatures, the production of CH₃O involves NO₂: CH₃ + NO₂ ? CH₃O. The sequence is followed by CH₃O ? CH₂O + H, CH₂O + OH ? HCO, HCO + O₂ ? HO₂, and H + O₂ ? HO₂. ? CH₂O + H, CH₂O + OH ? HCO, HCO + O₂ ? HO₂, and H + O₂ ? HO₂.