Simple laser vision sensor calibration for surface profiling applications

Due to the relatively large structures in the Oil and Gas industry, original equipment manufacturers (OEMs) have been implementing custom-designed laser vision sensor (LVS) surface profiling systems as part of quality control in their manufacturing processes. The rough manufacturing environment and the continuous movement and misalignment of these custom-designed tools adversely affect the accuracy of laser-based vision surface profiling applications. Accordingly, Oil and Gas businesses have been raising the demand from the OEMs to implement practical and robust LVS calibration techniques prior to running any visual inspections. This effort introduces an LVS calibration technique representing a simplified version of two known calibration techniques, which are commonly implemented to obtain a calibrated LVS system for surface profiling applications. Both calibration techniques are implemented virtually and experimentally to scan simulated and three-dimensional (3D) printed features of known profiles, respectively. Scanned data is transformed from the camera frame to points in the world coordinate system and compared with the input profiles to validate the introduced calibration technique capability against the more complex approach and preliminarily assess the measurement technique for weld profiling applications. Moreover, the sensitivity to stand-off distances is analyzed to illustrate the practicality of the presented technique.     

Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.     

Optimal intervention under stress scenarios: A case of the Korean financial system

We consider optimal intervention methods under budget constraints when financial systems face economic shocks. We propose two policies formulated by mixed-integer linear programs where regulators inject cash into institutions. One is to minimize systemic losses, and the other is to minimize the number of defaulting institutions. Using publicly available data on the Korean financial system, we construct its entire network and apply stress scenarios to the system to compare the performances of intervention strategies and derive insights on their workings.     

Catalytic Platinum Nanoparticles Decorated with Subnanometer Molybdenum Clusters for Biomass Processing

The development of improved technologies for biomass processing into transportation fuels and industrial chemicals is hindered due to a lack of efficient catalysts for selective oxygen removal. Here we report that platinum nanoparticles decorated with subnanometer molybdenum clusters can efficiently catalyze hydrodeoxygenation of acetic acid, which serves as a model biomass compound. In contrast with monometallic Mo catalysts that are inactive and monometallic Pt catalysts that have low activities and selectivities, bimetallic Pt–Mo catalysts exhibit synergistic effects with high activities and selectivities. The maximum activity occurs at a Pt to Mo molar ratio of three. Although Mo atoms themselves are catalytically inactive, they serve as preferential binding anchors for oxygen atoms while a catalytic transformation proceeds on neighboring surface Pt atoms. Beyond biomass processing, Pt–Mo nanoparticles are promising catalysts for a wide variety of reactions that require a transformation of molecules with an oxygen atom and, more broadly, in other fields of science and technology that require tuning of surface–oxygen interactions.     

Determination of tensile strength of UHMWPE fiber-reinforced polymer composites

Quasi-static tensile test of UHMWPE fiber-reinforced composite laminate is challenging to perform due to low interlaminar shear strength and low coefficient of friction. Tensile tests proposed in the literature were conducted and limitations associated with each method led to the evolution of a new method. Tensile test of single-ply was realized as the best representative of tensile strength of a composite than tensile test of UHMWPE laminate. A fixture was developed for single-ply tests which increased friction and provided the mechanical constraint to slipping. The fixture is easy to fabricate and has provided repeatable results for eight grades of UHMWPE fiber-based (0/90) fabrics. Reported tensile strengths are in quite high range of 900–1500 MPa.     

Measuring densities of polymers by magneto-archimedes levitation

In magneto-Archimedes levitation, a polymer can be levitated to a balanced position, and its levitation height is mainly related to the density of the polymer. Here, a novel method for measuring the density of polymers based on magneto- Archimedes levitation is proposed. For a designed measurement device, an equation can be fitted by a series of experiments with standard density glass beads. Then, the polymer's density can be calculated via the equation. In this paper, a device with magnets at a distance of 60 mm was chosen as an example. Experimental results showed that the proposed method could measure all types of polymer with an accuracy of 0.002–0.01 g/cm³. Moreover, the proposed method can clearly distinguish between polymers with small density differences (<0.03 g/cm³). Because of its high accuracy, high sensitivity, low cost and convenience, the proposed method could be widely used in polymer testing, especially in density-based testing.     

High frequency circular translation pin-on-disc wear testing of UHMWPE using a ball-on-flat contact along a hypotrochoidal track

To intensify experimental research within the field of orthopaedic tribology, a three-station, dual motion, high frequency (25.3 Hz) circular translation pin-on-disc wear test device was recently introduced. In the present study, the pins were CoCr with a spherical, polished bearing surface of 28 mm radius, whereas the flat discs were conventional UHMWPE. This configuration was intended to simulate the wear mechanisms of total knee prostheses. The number of wear cycles run was as high as 200 million. The mean wear rate was 0.35 mg per one million cycles (0.77 mg/24 h) which corresponded to a mean wear factor of 3.5 × 10⁻⁶ mm³/Nm. The study provided further proof that a wear test for orthopaedic implant materials can be accelerated by substantially increasing the cycle frequency, provided that the sliding velocity remains close to the values obtained from biomechanical studies. Hence, the moderate frictional heating will not lead to unrealistic wear mechanisms.     

Characterization of solar cells by thermal transient testing

The current paper deals with the application of thermal transient testing as a characterization tool for solar modules. Based on the measurement of different samples (concentrator solar cell, single junction silicon solar cell) we prove the applicability of this measurement technique and address some specific issues of the characterization of solar cells by the thermal transient method.From the measurement metrics such as junction-to-base plate thermal resistance and thermal capacitance(s) can be derived and can serve as a basis of a multi domain solar cell model. The used technique also enables us to verify the quality of attachment layers in a solar module allowing fair quality control and reliability analysis of these devices. Finally a method is proposed to regain the data that is covered by the initial electric transient following the power step. This initial electric transient can be high in large surface devices like solar cells, and covers valuable data describing the structure near to the p–n junction. To eliminate this, simulated transients were fitted to the part of the actual measured thermal transient where the electric transient already decayed. This way the part of the thermal transient that was covered by the electric transient can be reconstructed.     

双波段红外探测设备同靶标共航路测试方法研究

针对双波段红外探测设备不同波段的探测要求,利用曳光管双波段辐射特性,提出无人机加载曳光管作为低空移动光电靶,实现同一靶标满足双波段测试要求;通过对无人机航路距离和航向的统筹设计,实现同一个飞行航次满足作用距离和目标数据精度等多个测试项目;文中对目标航迹真值精度进行深入分析,总结出在不同条件下,航路、航向及布站等相关参数的关联和设置方法,为该测试项目组织实施提供充分的技术准备和选择空间。     

基于子路径扩展的不可达路径检测方法

不可达路径是造成软件测试资源消耗的一个重要方面.在路径测试之前,检测程序中的不可达路径可以有效节约软件测试资源.提出了一种基于子路径扩展的不可达路径静态检测方法.该方法首先生成程序的子路径集,将路径的可达性问题转换为不等式组的求解问题.使用约束求解器判断子路径的可达性,可以分为:可达子路径,不可达子路径和无法判定三个部分,并对后面两部分的子路径扩展出的路径做二次可达性检测,最终获得程序中所有路径的可达性信息.可达性检测工作主要在子路径集上进行,因此有效地解决了路径爆炸问题.实验结果表明本文方法可以准确有效地检测出程序中的不可达路径.