基于LXI的热电阻与热电偶信号故障注入器设计

为满足装备试验中的热电阻和热电偶信号自动故障注入的要求,设计了基于LXI的热电阻与热电偶信号故障注入器。通过将故障注入器串接入热电阻和热电偶信号传输线路,模拟多种热电阻和热电偶信号传输过程中的故障类型,实现对被测设备热电阻和热电偶信号的仿真。该故障注入器已应用于多类型装备的测试性验证试验中,具有良好的推广价值和应用前景。     

基于深度学习的故障检测方法

针对传统故障诊断方法中特征提取技术难度大、故障样本获取困难等问题,在深度学习计算框架下提出了一种半监督训练的故障检测方法,利用深度信念网络中的受限波茨曼机堆栈结构实现了数据高层特征的自动提取,结合支持向量数据描述方法实现了异常数据检测,只需利用正常工况的数据样本进行网络训练和模型拟合,无需故障样本数据,也无需人工干预进行信号特征提取,即能实现对故障数据进行的实时检测和判别。经采用标准轴承实验数据的三组故障数据进行验证,故障识别率达到100%,具有很强的工程应用价值。     

Three-dimensional transient thermoelectric currents in deep penetration laser welding of austenite stainless steel

The existence of thermoelectric currents (TECs) in workpieces during the laser welding of metals has been common knowledge for more than 15 years. However, the time-dependent evolutions of TECs in laser welding remain unclear. The present study developed a novel three-dimensional theoretical model of thermoelectric phenomena in the fiber laser welding of austenite stainless steel and used it to observe the time-dependent evolutions of TECs for the first time. Our model includes the complex physical effects of thermal, electromagnetic, fluid and phase transformation dynamics occurring at the millimeter laser ablated zone, which allowed us to simulate the TEC, self-induced magnetic field, Lorentz force, keyhole and weld pool behaviors varying with the welding time for different parameters. We found that TECs are truly three-dimensional, time-dependent, and uneven with a maximum current density of around 10⁷ A/m² located at the liquid-solid (L/S) interface near the front or bottom part of the keyhole at a laser power of 1.5 kW and a welding speed of 3 m/min. The TEC formed three-dimensional circulations moving from the melting front to solidification front in the solid part of workpiece, after which the contrary direction was followed in the liquid part. High frequency oscillation characteristics (2.2–8.5 kHz) were demonstrated in the TEC, which coincides with that of the keyhole instability (2.0–5.0 kHz). The magnitude of the self-induced magnetic field and Lorentz force can reach 0.1 mT and 1 kN/m³, respectively, which are both consistent with literature data. The predicted results of the weld dimensions by the proposed model agree well with the experimental results. Our findings could enhance the fundamental understanding of thermoelectric phenomena in laser welding.     

汶川地震断裂带断层泥矿物拉曼光谱特征

系统测定了汶川地震断裂带深溪沟剖面断层泥中石英和方解石颗粒的拉曼谱峰。测试结果表明,受到断层滑动、 断裂带构造挤压应力作用,所有样品的特征拉曼谱峰向高波数偏移。所测样品中微裂隙发育、 与绿泥石等粘土矿物共生的石英颗粒的464 cm-1谱峰向高波数偏移量为2.50 cm-1,而比较完整的纯净石英颗粒的464 cm-1谱峰偏移量为3.78 cm-1。这可能是由于石英颗粒早期发育大量微裂隙,并填充了松散的粘土矿物,增加了石英颗粒的表面积,从而加速了石英内应力的释放。断层泥中方解石颗粒的1 085 cm-1谱峰向高波数偏移2.70 cm-1,为汶川8.0级地震断层面所受构造压应力所致。根据方解石颗粒拉曼谱峰的变化及已有的实验数据,估计汶川地震发生时断层面所受压应力的下限为496 MPa。研究表明,对断裂带内矿物颗粒进行拉曼谱峰测试,可以为推测断层活动时断层面所受到的力学机制提供依据。     

沿岸流不稳定多模式运动的理论分析

目前对沿岸流不稳定研究比较成熟的理论基础是线性不稳定理论,该理论假定增长率最大的不稳定模式决定着沿岸流的波动特性,但实验分析结果表明对有些情况下该假定难以解释实验中观测到的情况.利用沿岸流不稳定运动的多模式理论分析了实验中观测到的情况.结果表明沿岸流速度剖面对于沿岸流不稳定运动模式影响很大,特别是速度剖面的变化会导致不稳定模式出现多个模式的情况,即增长率曲线出现多于两个峰的情况.用解析的速度剖面分析了速度剖面前剪切和后剪切同时变化及单独变化对于沿岸流不稳定多模式运动的影响.结果表明对于坡度为1:100的平直斜坡的情况用前剪切不稳定理论可以解释其观测到的现象.      

Time-dependent MHD Couette flow of rotating fluid with Hall and ion-slip currents

The unsteady magnehydrodynamics (MHD) Couette flow of an electrically conducting fluid in a rotating system is investigated by taking the Hall and ion-slip currents into consideration.The derived fundamental equations on the assumption of a small magnetic Reynolds number are solved analytically with the well-known Laplace transform technique.The unified closed-form expressions are obtained for the velocity and the skin friction in the two different cases of the magnetic field being fixed to either the fluid or the moving plate.The effects of various parameters on the velocity and the skin friction are discussed by graphs.The results reveal that the primary and secondary velocities increase with the Hall current.An increase in the ion-slip parameter also leads to an increase in the primary velocity but a decrease in the secondary velocity.It is also shown that the combined effect of the rotation,Hall,and ion-slip parameters determines the contribution of the secondary motion in the fluid flow.     

硫化物矿床断层微粒的红外光谱分析

前人的研究着重于断层活动对矿体空间位置的改造或成矿方面,忽视了硫化物矿石及其围岩在断层活动过程中形成微粒的研究。文章采用傅里叶变换红外光谱和扫描电镜分析硫化物矿床断层微粒,结果表明,样品主要由含水硫酸钙、含水硫碳酸钙、石英、绢云母和有机质组成。其中含水硫碳酸钙是新发现的矿物。这反映在断层活动过程中,硫化物矿物中的S2-发生了氧化转变为S6+,形成含水硫酸钙,或者含水硫碳酸钙矿物。研究结果不仅可应用于该类型矿床找矿勘探,而且对于矿石利用等方面也是有意义的。另外,文章还讨论了含水硫酸钙、含水硫碳酸钙的红外光谱鉴定特征,提出红外光谱分析技术十分适合断层活动形成的含水硫酸钙和含水硫碳酸钙微粒的分析。     

大冶铁矿东露天采场滑坡稳定性分析——以F25断裂滑脱带内滑坡群为例

摘  要 大冶铁矿东露天采场二区滑坡群位于F25断裂滑脱带内,属人工开采形成的高陡岩质边坡。断裂带内闪长岩和铁矿石被破碎成典型的角砾岩和碎粉岩,节理发育程度较高。滑坡群由三个主滑体及若干碎裂岩土体组成,平面平均长度约138m,平均宽度约120m,高差约85m,整体坡度约36°,总体积约1.1×107m3,下伏基岩为粉砂质泥岩,滑体组成物质为粉质粘土夹碎石块。运用自然历史分析法和工程地质类比法讨论了滑坡的破坏机理,认为该滑坡群的形成和发展是岩土类型和性质、岩体结构及地质构造、地形地貌、水、诱发因素等综合作用的结果。运用极限平衡方法对其中一典型滑坡在现状、暴雨、爆破及暴雨爆破联合作用四种工况下的稳定性进行综合分析和评价,所得稳定性系数分别为1.256、0.961、1.198、0.954,计算结果表明降雨是控制该滑坡稳定性的主要外因。针对该滑坡的实际情况,提出了避免采用抗滑桩加固、避免暴雨时地下爆破作业、在滑坡后壁及坡面上设置截水沟和排水沟、水泥砂浆嵌缝、减荷反压及坡面绿化等防治方案建议。     

汶川地震震后大成都地区断裂带活动性氡气测量分析评价

本文运用活动断裂剖面上的土壤氡气浓度测量,对大成都地区断裂的位置、范围和活动性进行监测,监测结果表明汶川地震对大成都地区断裂带有较大的影响。通过对北川断裂虹口剖面、彭灌断裂小渔洞剖面、彭灌断裂中坝剖面、彭灌断裂白鹿剖面以及新津-蒲江断裂剖面进行监测,从测量结果分析可知：断裂剖面土壤氡浓度背景高于无断裂带地区,且受地震影响较大,距汶川地震震中越近,断裂剖面土壤氡浓度值越高;断裂剖面氡浓度异常阈值与背景值之比均不大于3,最大值与背景值之比均小于5。结合测量地点的地形、表层土壤结构等地质条件,对大成都地区震后活动断裂的相对活动性的强弱进行科学评价,认为目前大成都地区并无活动性极强的断裂,且北川断裂与新津-蒲江断裂的活动性高于彭灌断裂。     

Tetrodotoxin: a brief history

Tetrodotoxin (TTX), contained in puffer, has become an extremely popular chemical tool in the physiological and pharmacological laboratories since our discovery of its channel blocking action in the early 1960s. This brief review describes the history of discovery of TTX action on sodium channels, and represents a story primarily of my own work. TTX inhibits voltage-gated sodium channels in a highly potent and selective manner without effects on any other receptor and ion channel systems. TTX blocks the sodium channel only from outside of the nerve membrane, and is due to binding to the selectivity filter resulting in prevention of sodium ion flow. It does not impairs the channel gating mechanism. More recently, the TTX-resistant sodium channels have been discovered in the nervous system and received much attention because of their role in pain sensation. TTX is now known to be produced not by puffer but by bacteria, and reaches various species of animals via food chain.(Communicated by Masanori OTSUKA, M.J.A.).