共查询到20条相似文献，搜索用时 31 毫秒
1.
黑盒测试和白盒测试都是软件测试的重要方法,黑盒测试的测试人员更偏重于业务方向,白盒测试的测试人员更偏重于实现方式;黑盒测试更注重整体,白盒测试更注重局部;它们是相辅相成的. 相似文献
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清康熙年间,汉口出现了一种由两淮盐商设立的专款“匣费”,主要用于逢迎官员。随着匣费逐渐增多,需要一种专门人员来管理匣费,这些人员多从商人中产生,所以被称为“匣商”。文章主要探析汉口匣商的性质、出现的时间、影响以及消失。通过对汉口匣商的研究有助于更加的了解两淮盐商这一群体。 相似文献
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为了确定预应力混凝土箱粱的极限承载能力,进行了预应力混凝土连续箱梁的破坏性试验,提出一种有限元损伤分析方法模拟箱梁结构行为.基于实体退化壳单元对箱梁进行模拟,并考虑了结构材料的非线性效应.由于预应力混凝土箱梁中通常存在大量曲线预应力钢筋,提出一种组合单元,并用该单元模拟箱梁中的预应力钢筋,该方法可使结构分析时单元数量大大降低.试验结果和理论分析对比表明:提出的方法能够有效地用于预应力混凝土连续箱梁的破坏性试验计算分析中;研究的旧桥依然存在较大的极限承载能力. 相似文献
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电子仪器设备机箱的可靠性设计 总被引：1，自引：0，他引：1
机箱是电子仪器设备的重要组成分,由于其具有防热、抗振、抗电磁辐射、美观外形等功能,因此机箱可靠性设计是仪器设计中具有重要意义。本文通过对机箱有关防热、抗振、抗辐射、美观外形的设计讨论,阐述了机箱可靠性设计的一般原则与措施,对仪器设备的机箱可靠性设计具有一定的指导与借鉴作用。 相似文献
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Box plots are frequently used, but are often misinterpreted by students. Especially the area of the box in box plots is often misinterpreted as representing number or proportion of observations, while it actually represents their density. In a first study, reaction time evidence was used to test whether heuristic reasoning underlies this misinterpretation. Moreover, it was tested whether this heuristic reasoning was caused by the saliency of the area of the box. In a second study, the effect of an intervention aimed at improving students' interpretation of the box plot on their heuristic reasoning about box plots was investigated. The results suggest that this misinterpretation of box plots is indeed due to heuristic reasoning and is very difficult to overcome. 相似文献
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建立我国农业支持保护体系,应加强农业绿箱政策,将黄箱政策转化为绿箱政策,试用蓝箱补贴政策等。同时国家要加强农业基础设施和生态工程建设,提高农业综合生产能力和可持续发展能力;完善对农民和农业生产补贴体系,增强农业国际竞争力;建立农业生产风险防范与保险机制,有效化解农业生产的自然和市场风险;放宽贸易管制,促进农产品出口;完善农业政策法规体系,实现对农业支持保护的制度化和法制化,为保证农民收入增长,促进农村发展提供制度保障。 相似文献
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Stephanie Lem Kathy Baert Eva Ceulemans Patrick Onghena Lieven Verschaffel Wim Van Dooren 《教育心理学》2017,37(10):1281-1300
The ability to interpret graphs is highly important in modern society, but has proven to be a challenge for many people. In this paper, two teaching methods were used to remediate one specific misinterpretation: the area misinterpretation of box plots. First, we used refutational text to explicitly state and invalidate the area misinterpretation of box plots. Second, we used multiple external representations (MERs): Histograms were used as an overlay on box plots in order to give students a better insight in the way box plots represent data distributions. Third, we combined refutational text and MERs. We found that refutational text was successful in improving students’ interpretation of box plots, but that the use of MERs did not improve students’ interpretation of box plots. The addition of MERs also did not increase the effect of refutational text. 相似文献
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S. Aslι Özgün-Koca 《Journal of Mathematics Teacher Education》2010,13(1):49-71
Although growing numbers of secondary school mathematics teachers and students use calculators to study graphs, they mainly
rely on paper-and-pencil when manipulating algebraic symbols. However, the Computer Algebra Systems (CAS) on computers or
handheld calculators create new possibilities for teaching and learning algebraic manipulation. This study investigated the
views of Turkish prospective secondary mathematics teachers on the use of advanced calculators with CAS in algebra instruction.
An open-ended questionnaire and group interviews revealed prospective teachers’ views and beliefs about when and why they
prefer three possible uses of CAS—black box, white box, or Symbolic Math Guide (SMG). The results showed that participants
mainly preferred the white box methods and especially SMG to the black box method. They suggested that while the black box
method could be used after students mastered the skills, the general white box method and SMG could be used to teach symbolic
manipulation. 相似文献
10.
王治雄 《黄冈职业技术学院学报》2021,(1):97-99
募捐时需要通过捐款捐物箱对现金及生活用品进行储藏,以便于后续工作人员进行收集和分类。针对市场上现有的捐款捐物箱自身稳定性差,且移动不便,当有易碎品捐赠时容易出现破碎等问题,通过设置缓冲装置和防滑装置,对其整体结构和关键部位进行了改良设计。新设计的捐款捐物箱,结构简单合理、具有较高的稳定性和安全性。 相似文献
11.
薄壁箱梁剪滞效应研究方法 总被引：3，自引：0，他引：3
探讨了研究箱梁剪滞效应的几种方法，即变分原理、比拟杆法、有限元法、模型试验，针对钢筋混凝土箱梁模型，着重介绍了运用箱梁模型试验研究剪力滞效应． 相似文献
12.
李富盈 《洛阳师范学院学报》2008,27(2):159-162
箱梁质量在桥梁施工中尤为重要。影响预制箱梁质量的主要因素有:施工工艺,原材料质量,施工人员的业务水平和素质等。本文结合洛南高速公路No.6标段汝河特大桥预制箱梁的施工情况,对施工工艺进行了分析。 相似文献
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胡志刚 《天津工程师范学院学报》2005,15(3):29-30,41
利用单片机控制发光二极管和光纤来模拟汽车自动变速器的油路、阀体及其故障现象,采用键盘和LED显示器进行人机交互,成功地模拟了自动变速器的核心技术--自动换档功能.该软件设计操作方便简单,使学生能够清晰地领会自动变速器的工作原理. 相似文献
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混凝土箱梁以其良好的结构整体受力性能在现代大跨桥梁结构中得到广泛的应用, 但迄今所修建的混凝土箱梁桥中, 在施工阶段或在运营阶段, 箱梁上均存在较多的由温度引起的开裂现象, 造成这一现象的主要原因是现有计算方法的不完善, 其中之一就是未考虑箱梁在温度荷载作用下的剪力滞效应。本文采用有限元法对大跨混凝土箱梁桥在温度荷载作用及自重作用下的剪力滞效应进行了详细的分析, 其结果表明在温度作用下, 箱梁翼板底面存在着较为严重的剪力滞现象, 并获得了箱梁在温度荷载作用下剪力滞效应的一般规律和初步结论,为箱梁的温度应力计算提供了参考。 相似文献
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After a 75-sec intratrial delay, rats that had been shown the location of hidden food within a rectangular box correctly dug at that location in a second identical box, which had been moved into the same position within the room. For some rats, the opposing ends of the boxes were differentiated by distinctive corner panels; for others, there were no panels. When, during the delay interval, the turntable supporting both boxes was rotated by more than 180°, so that the second box no longer took the place of the first box within the room, the rats showed performance decrements. Nevertheless, 4 subjects selected the correct location significantly more often than the rotationally equivalent location, which corresponds to the correct location when the ends of the box are confused. The amount of rotation had no significant effect for any rat. In a final phase, the rats were denied perceptual access to cues outside the test box, which now had differentiating corner panels for all rats. Despite the distinctive panels, no rat showed a significant difference between correct digs and rotational errors; that is, no rat reliably distinguished one end of the box from the other. Results confirm previous findings that rats rely primarily on environmental shape to establish their heading. They ignore distinctive features of the surfaces that define environmental shape, even when the shape by itself is insufficient to establish a unique orientation. 相似文献
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钢-混凝土组合箱梁日照温差的实测和理论分析(英文) 总被引：2，自引：0，他引：2
为了探讨和验证钢-混凝土组合截面日照温度场的计算方法, 依托某大跨径三跨变截面连续箱梁桥, 对钢-混凝土组合箱梁的日照温度场进行了现场实测. 通过实测发现, 由于各腹板接受太阳漫散射的程度不同, 外侧钢梁温度普遍高于内侧箱梁, 且钢箱的整体平均温度数值与箱内空气基本吻合. 在此基础上借助ANSYS有限元计算软件, 根据不同位置钢腹板所处环境条件确定了各自的太阳辐射和对流换热情况, 进行了综合边界条件的瞬态热分析. 各测点理论计算结果与实测数据能较好地吻合, 温度差值在2℃以内, 说明了理论计算方法的可靠性, 为后续深入研究钢-混凝土组合截面日照温度场奠定了基础. 相似文献
20.
石永秀 《唐山师范学院学报》2013,(5):70-72
跳箱练习和半程跳远练习是跳远训练的重要练习方法,对跳远运动员技术的形成和专项力量训练非常有意义。通过图像解析法和数理统计法对半程跳远、跳箱和跳远起跳技术从运动学角度对膝关节进行分析,得出跳箱练习与其它两者有显著差异。 相似文献