Evaluation of system models for an endoscopic fringe projection system

To be able to perform inline inspection of complex geometries, which exhibit for example undercuts or internal structures, a new endoscopic micro fringe projection system has been developed. It is designed to perform areal measurements for tool inspection inside the limited space of metal forming presses by employing flexible image fibers to couple the measurement system’s camera and projector to a compact sensor head. The projector features a laser light source and a digital micro-mirror device to generate high-contrast fringe patterns. To increase the depth of field of the sensor heads, custom gradient-index lenses have been designed as an approximation to the Scheimpflug principle. Challenges arise for both calibration and phase measuring algorithms from the optics, as well as from the reduction in resolution introduced by the fiber bundles. This paper presents an evaluation of two different system models for the endoscopic fringe projection system, which are based on the pinhole camera model and a black box model. An automated calibration process, which gathers the calibration data for two calibration algorithms that are robust to artifacts introduced by the optical path, is demonstrated. Based on a comparison of measurements, differences between the two modeling approaches are discussed. Finally, results of measurements of a demonstrational metal forming tool are shown as an application example.     

α-Stirling hydrogen engines for concentrated solar power

α-Stirling engines are receiving more and more attention for applications of concentrated solar power in small power installations (15–30 kW). The design of these engines has not experienced in recent years the breakthrough needed to deliver close to the Carnot Cycle energy conversion efficiencies. The delivered efficiencies are limited to mid-to-high 20% in the typical installations “Dish Stirling”. Here we review the latest studies made on α-Stirling engines, unfortunately mostly based on theoretical models of limited reliability, but also including very few examples of Computer-Aided Engineering (CAE) modeling followed by prototyping and testing. Finally, we present in detail one CAE model of an α-Stirling engine delivering energy conversion efficiencies of 42% with hydrogen as working fluid and adopting one hot cylinder, one cold cylinder, and one regenerator, with the hot fluid temperature of 800 °C. This efficiency is much higher than current air microturbines, which may deliver efficiencies of only about 20% working at much lower temperatures.     

Effect of Halloysite Nanotubes as Novel Nanofiller on Peroxide- and Electron Beam Radiation-Initiated Polyphosphazene Elastomer

A tubelike, naturally occurring halloysite clay mineral (HNTs) incorporated polyphosphazene (PPZ) elastomeric nanocomposites had been electron beam radiated and thermally treated for certain applications. To improve the dispersion of raw HNTs (H), an organosilane modifier had been exploited. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) technique were utilized for plausible interaction and intercalation. The efficiency of electron beam radiation over chemical initiation for intra and inter chain network formation within the resin was substantiated through oil and solvent resistance studies. Effective delay in mass transport as compared to the virgin elastomer was observed through thermal analysis.     

梁式窑煤粉喷吹系统设计

结合梁式窑工艺流程,详细介绍了煤粉输送和喷吹系统的工艺及设备组成。煤粉安全、可靠地输送到煤粉仓,并喷射到烧嘴是保证钙灰生产的关键。     

抗(耐)震压力表液压伺服脉动校验装置应用研究

执行SY/T 6817—2010《抗(耐)震压力表校准方法》对抗(耐)震压力表进行校验时,需要在量程的30%～40%之间的一个检验点上施加正弦波脉动压力,其幅度不大于该点压力值的10%,脉动频率为（60±5）次/min。为了获得这样的脉动压力源,采取气驱液泵预压产生检验点基准值,及利用液驱液增压缸产生10%增幅的高压值,通过伺服液压控制增压缸活塞的往复运动产生波动范围在基准值和高压值之间的正弦脉动。研制的校验装置脉动频率和幅度设定方便、环境参数影响小,通过工控机采集卡控制,显示界面明晰、控制精度高,适合于试验室、检定室校验抗(耐)震压力表使用等。     

从普通梁、扁梁到板带梁

本文介绍一种新颖的高层楼盖结构——板带梁,它将扁梁与无梁楼盖二种技术优点结合起来,变成一种新的梁板体系。这种板带梁克服了无梁楼盖设计中板梁分界线和配筋分区划分的模糊性,又将扁梁的高度再压缩从而又进一步达到加大室内净高或降低层高的目的。     

碳纤维加固梁设计的补充建议

根据我国对碳纤维布加固梁的试验研究成果 ,对碳纤维加固梁的破坏机理及设计要求进行了分析 ,并结合碳纤维产品的特性及外界环境、荷载形式可能对其产生的影响 ,对碳纤维布加固梁设计提出了一些补充建议 ,可供设计及工程人员参考。     

再生粗骨料混凝土梁抗弯性能试验研究

通过对3根相同配筋率、相同混凝土抗压强度、不同再生粗骨料取代率的再生混凝土简支梁的抗弯试验,探讨了再生混凝土受弯构件正截面受力变形性能和破坏特征。试验结果表明:再生混凝土梁正截面在受力过程中,仍具有弹性、开裂、屈服和极限4个明显特征;正截面平均应变服从平截面假定;相同条件下,再生混凝土梁的开裂弯矩和极限抗弯承载能力接近于普通混凝土受弯构件,抗弯刚度小于普通混凝土受弯构件。最后,本文根据现行《混凝土结构设计规范》(GB50010-2002)提出的普通混凝土梁的计算公式,验算了再生混凝土梁的开裂弯矩、极限弯矩、挠度和最大裂缝宽度。初步验算结果表明,除极限弯矩计算公式外,普通混凝土梁的开裂弯矩、挠度和最大裂缝宽度计算公式均不再适用于再生混凝土梁。     

高层建筑不同强度等级混凝土梁柱节点的处理方法

针对高层建筑中常见的梁柱混凝土强度等级不同的情况,参考国内外资料,并结合现场实践,对其抗震性进行分析,并提出设计及施工建议。