防止长输管道焊接裂纹

在目前长输管道焊接中所出现的焊接缺陷、表面裂纹、跟部裂纹、层间裂纹、对各种裂纹分析和防止裂纹产生措施对裂纹的返修方法。     

渗碳淬火齿轮磨削裂纹成因与防止措施

通过对磨削裂纹形成原因的分析,得出磨削裂纹的产生主要是工件不良组织形态在磨削热的作用下,残余应力与热应力相互作用的结果,并归纳出齿轮磨削裂纹产生的一些防止措施。     

矿用圆环链临焊缝部位的裂纹分析

本文对矿用圆环链临焊缝部位在焊接过程中产生的裂纹进行了分析。结果表明此裂纹主要有两类:即撕裂型裂纹和击穿型裂纹。并对这两种裂纹产生的原因及形成机理进行了综合分析,提出了一些防止措施。     

球罐焊接过程中冷裂纹的产生及控制措施

本文分析了球罐焊接冷裂纹产生的原因,提出了在球罐施工中防止冷裂纹产生的具体措施,经现场施工验证,该措施较好的解决了问题,保证了球罐的安装质量。     

激光熔覆层裂纹问题的研究

由于激光熔覆技术的一些特点,熔覆处理后材料表面极易形成裂纹,成为激光熔覆技术工业化应用急需解决的问题。本文系统地描述了激光熔覆层裂纹的形成机理,归纳了熔覆层裂纹的影响因素,总结了目前抑制裂纹产生的主要措施,为防止裂纹的产生提供了理论与实践依据。     

球罐焊接过程中冷裂纹的产生及控制措施

本文分析了球罐焊接冷裂纹产生的原因,提出了在球罐施工中防止冷裂纹产生的具体措施,经现场施工验证,该措施较好的解决了问题,保证了球罐的安装质量。     

高温再热器穿顶棚管裂纹原因分析及割密封释放应力的应急处理方案和结构改造方案

通过对高温再热器穿墙管与顶棚密封盒焊缝处产生的裂纹进行分析，找出裂纹产生的主要原因，从而采取有效措施，防止类似裂纹再次发生，确保机组安全运行。     

冲压模具刃口修磨产生缺陷的原因及消除

本文较全面地分析了冲压模具磨损后,修磨时磨削裂纹产生的原因以及防止模具修磨时产生裂纹的措施,在实际生产过程中对提高模具的使用寿命、提高生产效率、降低生产成本具有一定的意义。     

磨削加工中的表面裂纹及其防止

对于磨削加工过程中零件表面产生裂纹的原因及防止措施进行了介绍。     

商品砼梁板结构施工早期裂纹控制初探

通过分析商品砼梁板结构裂纹产生的规律、产生的原因,初步得出一些防止裂纹的技术措施。防治梁板结构裂纹的产生,首先要控制砼的生产质量,包括原材料的选用和原材料的质量控制、砼配合比及其生产的控制:其次是施工质量的控制,包括布料、振捣、抹压、养护、幼令砼保护,拆模。只要各部门各环节共同努力、精心配合才能凑效,通过实践证明只要努力裂纹是可以控制在最小范围的,或者说是可以基本得到控制的。     

A basal ganglia pacemaker formed by the subthalamic nucleus and external globus pallidus.

The subthalamic nucleus of the basal ganglia (STN) is important for normal movement as well as in movement disorders. Lesioning or deep-brain stimulation of the STN can alleviate resting tremor in Parkinson's disease. The STN and its target nuclei display synchronized oscillatory burst discharge at low frequencies, some of which correlate with tremor, but the mechanism underlying this synchronized bursting is unknown. Here we show that the excitatory STN and inhibitory, external globus pallidus (GPe) form a feedback system that engages in synchronized bursting. In mature organotypic cortex-striatum-STN-GPe cultures, neurons in the STN and GPe spontaneously produce synchronized oscillating bursts at 0.4, 0.8 and 1.8 Hz. Pallidal lesion abolishes this bursting, whereas cortical lesion favours bursting at 0.8 Hz. Pallidal bursts, although weaker than STN bursts, were required for synchronized oscillatory burst generation by recruitment of subthalmic rebound excitation. We propose that the STN and GPe constitute a central pacemaker modulated by striatal inhibition of GPe neurons. This pacemaker could be responsible for synchronized oscillatory activity in the normal and pathological basal ganglia.     

无缝钢管产品水压实验爆裂原因分析

对无缝钢管产品水压实验过程中发生的9例典型爆裂事故产生原因进行了宏观和微观综合分析.结果表明:引发钢管产品水压实验爆裂均与管体局部存在某种缺陷有关.连铸坯缺陷包括表面裂纹、表面存在保护渣和增碳、表面渗铜、中心偏析和内部夹杂物偏聚等;轧管缺陷包括表面划伤、壁厚不均和偏薄等;管加工缺陷包括表面淬火裂纹、热处理组织异常、屈服强度偏低、管端螺纹加工精度差等.针对分析结果,提出了改进措施.     

Detection of bursts in neuronal spike trains by the mean inter-spike interval method

Bursts are electrical spikes firing with a high frequency, which are the most important property in synaptic plasticity and information processing in the central nervous system. However, bursts are difficult to identify because bursting activities or patterns vary with physiological conditions or external stimuli. In this paper, a simple method automatically to detect bursts in spike trains is described. This method auto-adaptively sets a parameter (mean inter-spike interval) according to intrinsic properties of the detected burst spike trains, without any arbitrary choices or any operator judgment. When the mean value of several successive inter-spike intervals is not larger than the parameter, a burst is identified. By this method, bursts can be automatically extracted from different bursting patterns of cultured neurons on multi-electrode arrays, as accurately as by visual inspection. Furthermore, significant changes of burst variables caused by electrical stimulus have been found in spontaneous activity of neuronal network. These suggest that the mean inter-spike interval method is robust for detecting changes in burst patterns and characteristics induced by environmental alterations.     

Rulkov神经元的的簇放电类型与分岔条件

讨论了Rulkov神经元产生锥形簇放电、方形簇放电及峰放电的非线性动力学特征,尤其是锥形簇放电的放电规律和动力学特征。指出产生锥形簇放电的关键在于鞍结点分岔和flip分岔,属于fold/flip型簇放电;而锥形簇放电的持续距离随着控制参数的增加而增大。首次给出了单个神经元产生各种簇放电的参数取值范围。     

中马村矿煤与瓦斯突出区域性预测研究

文章以焦作中马村矿为实施矿井，在已有突出预测工作的基础上，通过对现有突出预测指标的灵敏度分析，利用计算机筛选煤与瓦斯突出敏感指标，应用数量化理论法建立煤与瓦斯突出预测的综合判据，使突出预测工作规范化、定量化、微机化，提高了突出预测的准确性和可靠性，为矿井科学化管理、提高矿井安全经济效益提供了技术依据。     

Neuronal pacemaker for breathing visualized in vitro.

Breathing movements in mammals arise from a rhythmic pattern of neural activity, thought to originate in the pre-B?tzinger complex in the lower brainstem. The mechanisms generating the neural rhythm in this region are unknown. The central question is whether the rhythm is generated by a network of bursting pacemaker neurons coupled by excitatory synapses that synchronize pacemaker activity. Here we visualized the activity of inspiratory pacemaker neurons at single-cell and population levels with calcium-sensitive dye. We developed methods to label these neurons retrogradely with the dye in neonatal rodent brainstem slices that retain the rhythmically active respiratory network. We simultaneously used infrared structural imaging to allow patch-clamp recording from the identified neurons. After we pharmacologically blocked glutamatergic synaptic transmission, a subpopulation of inspiratory neurons continued to burst rhythmically but asynchronously. The intrinsic bursting frequency of these pacemaker neurons depended on the baseline membrane potential, providing a cellular mechanism for respiratory frequency control. These results provide evidence that the neuronal kernel for rhythm generation consists of a network of synaptically-coupled pacemaker neurons.     

煤矿矿井突水水源的多元矩阵模型分析

 针对煤矿矿井突水对煤矿安全生产的不利影响,基于水化学分析结果,建立多元混合模型模型,分析计算矿井突水水样,并与传统的BP 神经网络原理和模糊综合评判法相对比,分析结果与矿山实际情况相符合。结果表明：多元混合模型不仅能准确分析出矿井突水水样主要来源,而且计算简单准确,受水化学分析样本量和离子种类数量限制较小,可以作为一种矿井突水水源判别工具在工程实践中应用。     

正拱环向开缝型爆破片的爆破性能

通过实验得出正拱环向开缝型爆破片的破坏机理,由此导出正拱环向开缝型爆破片的爆破压力计算公式。公式计算值与实验值相比,误差在±5%以内,可以满足工程应用的要求。     

LPJ9．5系列焊接拉伸型爆破片起爆误差控制

LPJ9．5系列焊接拉伸型爆破片装置具有结构紧凑、起爆压力调节方便等优点，因而被大量应用于石油和天然气钻采设备上．本文着重论述删9．5系列焊接拉伸型爆破片装置的结构特点、影响爆破片起爆精度的主要因素以及提高起爆精度的措施．实践表明：LPJ9.5系列焊接拉伸型爆破片的起爆误差及其控制对象主要在于膜片材料的物理性能和厚度、排放口径加工精度、下夹持环的孔口圆角半径尺寸以及焊接方法和焊接参数．     

太原西峪煤矿下组煤开采底板奥灰水突水影响因素分析

在论述太原西峪煤矿矿井水文地质条件的基础上,重点分析了构造、底板岩性组合、底板破坏和水压等4个因素对底板突水的影响,指出含水层的富水性和隔水层厚度及结构是决定是否突水的基本因素,水压的大小是底板突水的基本条件,而构造和矿压从不同角度对底板起到了激化和促进作用,是底板突水的决定和控制因素。