某低温风洞用高强不锈钢弯刀小试件生产实践

某低温风洞弯刀采用00Cr12Ni10MoTi马氏体时效不锈钢制造(代号:S03).分别采用构筑成形和三联特冶(真空感应熔炼+真空自耗电弧熔炼+电渣重熔)工艺路线研究了10 t级S03钢小试件钢锭制备工艺.通过X射线衍射(XRD)、扫描电镜(SEM)和拉伸、冲击等评价方法,分别研究了冶炼和热处理工艺对S03钢组织及力学...     

基于分布式架构及PAC技术的风洞测试及控制系统设计

为准确分析飞行器气动载荷的实际变化规律,降低舱门、舱体类结构部件所受到的冲击载荷作用,设计基于分布式架构及PAC技术的风洞测试及控制系统。在Hadoop集群安装环境中,设置HBase加载模块,借助压电传感器结构与压力控制子回路,实现对加热器供气管路的指向性连接,完成风洞测试控制系统分布式架构集群的建立,解决飞行器舱门及舱体结构的气动载荷获取问题。以驱动性程序作为软件控制基础,将所有待处理的传感器信息及测试数据显示至相同控制界面中,实现对风洞测试控制信号的准确分析,完成基于PAC技术的风洞测试自适应控制研究。仿真实验表明,不断增大压电传感器所承受的气动载荷总量,在风洞测试控制系统的支持下,舱门、舱体所受的实际冲击载荷作用均下降至4000GB左右,能够满足缓解飞行器气动载荷压力的测试初衷。     

隧道施工方法探讨（下）

针对地矿部门的经济状况和工程需要，分析了几种拱架型式的优缺点，并介绍了组装式拱架在八盘岭、安楚等双线公路隧道工程中的应用情况。最后还指出了在进行拱架设计时应注意的几个问题。     

多特征融合的行为识别模型

目的 视频行为识别和理解是智能监控、人机交互和虚拟现实等诸多应用中的一项基础技术,由于视频时空结构的复杂性,以及视频内容的多样性,当前行为识别仍面临如何高效提取视频的时域表示、如何高效提取视频特征并在时间轴上建模的难点问题。针对这些难点,提出了一种多特征融合的行为识别模型。方法 首先,提取视频中高频信息和低频信息,采用本文提出的两帧融合算法和三帧融合算法压缩原始数据,保留原始视频绝大多数信息,增强原始数据集,更好地表达原始行为信息。其次,设计双路特征提取网络,一路将融合数据正向输入网络提取细节特征,另一路将融合数据逆向输入网络提取整体特征,接着将两路特征加权融合,每一路特征提取网络均使用通用视频描述符——3D ConvNets （3D convolutional neural networks）结构。然后,采用BiConvLSTM （bidirectional convolutional long short-term memory network）网络对融合特征进一步提取局部信息并在时间轴上建模,解决视频序列中某些行为间隔相对较长的问题。最后,利用Softmax最大化似然函数分类行为动作。结果 为了验证本文算法的有效性,在公开的行为识别数据集UCF101和HMDB51上,采用5折交叉验证的方式进行整体测试与分析,然后针对每类行为动作进行比较统计。结果表明,本文算法在两个验证集上的平均准确率分别为96.47%和80.03%。结论 通过与目前主流行为识别模型比较,本文提出的多特征模型获得了最高的识别精度,具有通用、紧凑、简单和高效的特点。     

地道通风在莫高窟游客服务中心空调系统中的应用

莫高窟地处甘肃省西北部的敦煌市,当地全年气候干燥,为自然除湿创造了有利的条件。介绍了莫高窟游客服务中心接待大厅地道通风的地道设计、运行工况、热舒适指标计算,计算结果表明,室内环境的热舒适状况能满足规范要求。     

新疆下坂地软岩隧洞的施工工艺

结合工程实例,总结、归纳并阐述软岩条件下下坂地隧洞的开挖、出碴、一次支护、永久衬砌的施工技术方案,施工参数、措施及注意事项。     

动力系统的智能化监测与安全保护设计

直升机旋翼模型风洞试验是高转速、高风险的动态试验,为保护试验的安全运行,必须实时、准确、可靠地监测试验台关键驱动设备-动力驱动系统及辅助系统的运行状态,并根据运行状态分级采取相应的保护措施。本文以动力系统主控PLC为基础,打通试验台各系统之间的信息孤岛,提出了一种基于历史数据分析的设备运行状态分级评价及风险评估方法,根据实时运行数据判断动力系统运行风险,给出安全操作建议。风洞试验应用效果表明本文构建的旋翼模型试验台动力系统智能监测与安全保护设计数据分析科学,状态监测实时,安全保护可靠。提高了直升机试验的安全可靠性。     

八钢2500m3高炉长寿管理措施

八钢A高炉受原燃料的影响,导致炉况顺行变差。通过对A高炉参数的监控和分析,在操作上抑制钛的析出,及时排出有害元素,活跃炉缸,优化炉前作业的参数,及时更换变形的风口中套来恢复送风参数,对侧壁热耦测量的高温区域采取压浆和冷却参数调整等相应的措施,实现了高炉顺行。     

The development of risk assessment models for carpal tunnel syndrome: a case-referent study

The present study developed risk assessment models for carpal tunnel syndrome (CTS) which can provide information of the likelihood of developing CTS for an individual having certain personal characteristics and occupational risks. A case-referent study was conducted consisting of two case groups and one referent group: (1) 22 work-related CTS patients (W-CTS), (2) 25 non-work related CTS patients (NW-CTS), and (3) 50 healthy workers (HEALTHY) having had no CTS history. The classification of CTS patients into one of the case groups was determined according to the type of insurance covering their medical costs. Personal characteristics, psychosocial stresses at work, and physical work conditions were surveyed by using a questionnaire tailor-designed to CTS (reliability of each scale ? 0.7). By contrasting the risk information of each case group to that of the referent group, three logistic regression models were developed: W-CTS/HEALTHY, NW-CTS/HEALTHY, and C-CTS/HEALTHY (C-CTS, the combined group of W-CTS and NW-CTS). ROC analysis indicated that the models have satisfactory discriminability (d′ = ;1.91 to 2.51) and high classification accuracy (overall accuracy = 83 – 89%). Both W-CTS/HEALTHY and C-CTS/HEALTHY include personal and physical factors, while NW-CTS/HEALTHY involves only personal factors. This suggests that the injury causation of NW-CTS patients should be attributable mainly to their ‘high’ personal susceptibility to the disorder rather than exposure to adverse work conditions, while that of W-CTS patients be attributable to improper work conditions and CTS-prone personal characteristics in combination.     

Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations

When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, ‘Pressure Variations on a Train – Where is the Threshold to Railway Passenger Discomfort?’ Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise.

Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.