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Wolff-Michael Roth Maria Elena Oliveri Debra Dallie Sandilands Juliette Lyons-Thomas Kadriye Ercikan 《International Journal of Science Education》2013,35(4):546-576
Even if national and international assessments are designed to be comparable, subsequent psychometric analyses often reveal differential item functioning (DIF). Central to achieving comparability is to examine the presence of DIF, and if DIF is found, to investigate its sources to ensure differentially functioning items that do not lead to bias. In this study, sources of DIF were examined using think-aloud protocols. The think-aloud protocols of expert reviewers were conducted for comparing the English and French versions of 40 items previously identified as DIF (N?=?20) and non-DIF (N?=?20). Three highly trained and experienced experts in verifying and accepting/rejecting multi-lingual versions of curriculum and testing materials for government purposes participated in this study. Although there is a considerable amount of agreement in the identification of differentially functioning items, experts do not consistently identify and distinguish DIF and non-DIF items. Our analyses of the think-aloud protocols identified particular linguistic, general pedagogical, content-related, and cognitive factors related to sources of DIF. Implications are provided for the process of arriving at the identification of DIF, prior to the actual administration of tests at national and international levels. 相似文献
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The development of DNA cryptography has contributed to the ability of solving many computationally difficult problems by offering the capability of executing calculations in parallel. This capability is used particularly in solving NP-complete problems or implementing cryptography and steganography solutions. Biological computation models based on bonds between nitrogen bases in nucleic acid chains that make up DNA structures can also be used to develop new solutions for smart information management. This study discusses new secret splitting techniques based on mathematical linguistic methods and designed for intelligently managing secret data within hierarchical structures. These techniques make use of information coding models found in the coding of DNA sequences. 相似文献
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黄振宇 《河南职业技术师范学院学报》2011,(5):75-78
单片机与PC机的通信有十分重要的实际意义.通过分析简化TCP/IP协议,使用KEILC51编制程序实现TCP/IP协议,并采用RTL8019AS芯片设计制作连接单片机与PC机连接的硬件电路,对单片机与PC机间的通信进行了研究.在对TCP/IP深入分析基础上,简化TCP/IP协议栈并嵌入到51单片机中,结合硬件电路进行了单片机端的IP设置、ping命令的使用,实现了单片机与PC主机的通信连接. 相似文献
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电子选举中的安全协议 总被引：1，自引：0，他引：1
随着因特网上出现的一些小范围的电子选举,电子选举开始引起人们的关注.而电子选举中的关键技术之一是电子选举协议的设计,特别是在多种投票方式下大规模电子选举协议的安全性问题.讨论了优秀的电子投票系统应该具备的特点,及如何通过密码协议来实现这些特点;对电子选举协议提出了新的分类方法,并考察了其优缺点;并对已有的许多电子选举协议进行了分类整理,有助于人们更好地理解这一领域内所面临的挑战和问题;同时对电子选举系统的设计也给出了一些建议. 相似文献
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提出了一种利用陷门单向函数的性质对TMN协议进行改进的一般形式,利用串空间理论证明了它的安全性,并给出了几个具体的实现形式. 相似文献
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随着网络技术的发展,以太网以其传输速度高、低耗、易于安装和兼容性好等优势,开始逐步进入工业控制领域。近年来在运动控制器领域新推出的基于以太网接口的独立式运动控制器就是以太网在工业控制领域的典型应用之一。此种应用场合,主控机和运动控制器均通过互联网作物理连接。主控机与控制器之间的指令和数据传输则须遵循以太网的通讯协议。由于主控机和目标运动控制器所处的网段可能连接有数百台网络设备,在传输指令和数据之前,必须解决在这数百台网络设备中找出所要控制的目标运动控制器,以便进一步实现主控机对目标运动控制器一对一地连接和控制。其中查找该目标运动控制器所耗的时间直接影响到运动控制器的控制速度和效率。本文在研究基于ICMP协议（Internet Control Message Protocol）和ARP协议（Address Resolution Protocol）的网络设备查找方法基础上,提出了一种新的高效、稳定的以太网控制器定位方法,并给出了相应的实验结果。 相似文献