New high-temperature copper alloys

New high-strength, high-temperature Cu-Ni-Si alloys have been developed using additions of Cr, Zr, and/or Ti. These new alloys remain as precipitation hardenable as the base alloy, but the main strengthening phase may be different than Ni₂Si (e.g., Cr₂Ti). Substantial increases in mechanical strength were observed at both room and high temperature (773 K) when additions of Cr+Zr+Ti and Cr+Zr were made. Industrial testing of these alloys indicated a sevenfold increase in the lifetime of lateral blocks in continuous casting equipment of copper alloys.     

一种检测电火花加工间隙状态的柔性方法

介绍了一种在数控电火花加工脉冲电源中实现间隙状态检测的柔性方法，具有阈值设置柔性、状态识别准确的特点，巧妙地用一个稳压二极管的钳位作用提高了间隙状态识别的精度，非常适合需经常改变加工参数的加工实验使用。     

Experiment and simulation study of 3D magnetic field sensing for magnetic flux leakage defect characterisation

Magnetic flux leakage (MFL) testing is widely used to detect and characterise defects in pipelines, rail tracks and other structures. The measurement of the two field components perpendicular to the test surface and parallel to the applied field in MFL systems is well established. However, it is rarely effective when the shapes of the specimens and defects with respect to the applied field are arbitrary. In order to overcome the pitfalls of traditional MFL measurement, measurement of the three-dimensional (3D) magnetic field is proposed. The study is undertaken using extensive finite element analysis (FEA) focussing on the 3D distribution of magnetic fields for defect characterisation and employing a high sensitivity 3-axis magnetic field sensor in experimental study. Several MFL tests were undertaken on steel samples, including a section of rail track. The experimental and FEA test results show that data from not only the x- and z-axes but also y-axis can give comprehensive positional information about defects in terms of shape and orientation, being especially advantageous where the defect is aligned close to parallel to the applied field. The work concludes that 3D magnetic field sensing could be used to improve the defect characterisation capabilities of existing MFL systems, especially where defects have irregular geometries.     

铁道车辆轮对超声波探伤半轴试块的研制

主要介绍了RD2、提速车和DF4轴型超声波探伤半轴试块的研制，同时介绍了主要的技术要求及制作工艺。该试块适用于在役轮轴超声波探伤，为现场检测提供了统一的探伤基准。     

车床静刚度计算机测试系统研制

在分析了车床的结构特点和车削工艺系统的受力情况和借鉴传统车床静刚度仪优点的基础上，研制了一套基于计算机控制的车床静刚度测试系统。系统由计算机作为信号检测、数据处理和控制核心，并配以精密位移传感器、压力传感器和步进电机及其驱动器等。实现了自动加载、卸载，采样，数据处理，直接绘制、显示和打印刚度曲线等功能。系统的成功研制为车床静刚度的测试提供了一种先进手段。实测结果表明，该系统具有自动化程度高、测试效率高、精度高、可靠性高、测试性能稳定的优点。     

百菌清及其三氟衍生物对番茄早疫病菌的室内抑菌活性比较

采用生长速率法测定了不同浓度的百菌清及其三氟衍生物对番茄早疫病菌Alternaria solani(Ell,et Mart.)Jones es Gmut的室内杀菌毒力。试验结果表明，百菌清及其三氟衍生物的ED50值分别为6089．89mg／L和156．43mg/L。，前者是后者的38．93倍。百菌清三氟衍生物的毒力明显高于百菌清。     

大面积水域浓度场测试方法及系统研究

针对大面积水域浓度场难以实现实时测量、测量精度不高等问题,采用了一种多通道荧光测试系统和方法。首先,基于单色光诱导荧光检测浓度(LIF)原理,使用探头获取离散点的浓度参数。然后,经总线或通信网络技术,将数百个测点连接起来。最后,通过数据总线或网络将采集的数据输送到中央测控计算机中,处理离散的数据后形成完整的浓度场。在恒定流浓度场中的试验结果表明,污染物测量相对误差均值不超过5%,单次测量相对误差最高值为8.33%,传感器线性度不超过5%,可检测的荧光素钠溶液浓度分辨率为0.001 ppm,系统测量稳定、精度较高。相较于其他浓度测量方法,该系统具有测量面积大、实时测量的优势,可为水污染防治等领域提供可靠的技术支撑。     

Testing scientific software: A systematic literature review

ContextScientific software plays an important role in critical decision making, for example making weather predictions based on climate models, and computation of evidence for research publications. Recently, scientists have had to retract publications due to errors caused by software faults. Systematic testing can identify such faults in code.ObjectiveThis study aims to identify specific challenges, proposed solutions, and unsolved problems faced when testing scientific software.MethodWe conducted a systematic literature survey to identify and analyze relevant literature. We identified 62 studies that provided relevant information about testing scientific software.ResultsWe found that challenges faced when testing scientific software fall into two main categories: (1) testing challenges that occur due to characteristics of scientific software such as oracle problems and (2) testing challenges that occur due to cultural differences between scientists and the software engineering community such as viewing the code and the model that it implements as inseparable entities. In addition, we identified methods to potentially overcome these challenges and their limitations. Finally we describe unsolved challenges and how software engineering researchers and practitioners can help to overcome them.ConclusionsScientific software presents special challenges for testing. Specifically, cultural differences between scientist developers and software engineers, along with the characteristics of the scientific software make testing more difficult. Existing techniques such as code clone detection can help to improve the testing process. Software engineers should consider special challenges posed by scientific software such as oracle problems when developing testing techniques.     

Global software testing under deadline pressure: Vendor-side experiences

ContextIn the era of globally-distributed software engineering, the practice of global software testing (GST) has witnessed increasing adoption. Although there have been ethnographic studies of the development aspects of global software engineering, there have been fewer studies of GST, which, to succeed, can require dealing with unique challenges.ObjectiveTo address this limitation of existing studies, we conducted, and in this paper, report the findings of, a study of a vendor organization involved in one kind of GST practice: outsourced, offshored software testing.MethodWe conducted an ethnographically-informed study of three vendor-side testing teams over a period of 2 months. We used methods, such as interviews and participant observations, to collect the data and the thematic-analysis approach to analyze the data.FindingsOur findings describe how the participant test engineers perceive software testing and deadline pressures, the challenges that they encounter, and the strategies that they use for coping with the challenges. The findings reveal several interesting insights. First, motivation and appreciation play an important role for our participants in ensuring that high-quality testing is performed. Second, intermediate onshore teams increase the degree of pressure experienced by the participant test engineers. Third, vendor team participants perceive productivity differently from their client teams, which results in unproductive-productivity experiences. Lastly, participants encounter quality-dilemma situations for various reasons.ConclusionThe study findings suggest the need for (1) appreciating test engineers’ efforts, (2) investigating the team structure’s influence on pressure and the GST practice, (3) understanding culture’s influence on other aspects of GST, and (4) identifying and addressing quality-dilemma situations.     

A Solder Alloy Filled Z-Axis Conductive Epoxy Adhesive

Epoxy adhesives filled with four different volume fractions of eutectic tin-bismuth solder alloy were prepared and the effect of filler content on the electrical and mechanical properties of these anisotropic electrically conductive adhesives was investigated. The results show that the adhesive containing the lowest amount of the filler alloy had the best combination of conductivity, insulation resistance and shear strength. The DSC-measurements suggested that the filler melts before the cure of the resin begins which allows the filler to wet and bond well to the conductors. This was verified by SEM/EPMA examinations. A temperature cycling test and high humidity, high temperature treatment were conducted on the best composite adhesive. The temperature variation had no effect on conductivity of the joints while humid and hot environment decreased the conductivity.