Pro/E工程剖视图与制图国标不相符合问题的解决方法

利用Pro/E三维模型与二维图形双向关联功能可以快速生成工程图,但由于在视图表达上有些方面不符合我国制图标准而影响其有效使用.本文针对Pro/E制作工程剖视图时所存在的与制图国标不相符合的问题,提出了解决这些问题的方法和技巧.     

SBS改性沥青

介绍了沥青的特性，改性沥青的种类与性能，以及丁苯嵌段共聚物改性沥青的相容性，溶胀性，分散性等方面的研究进展，并提出了发展建议。     

面向口语统计语言模型建模的自动语料生成算法

在资源相对匮乏的自动语音识别(Automatic speech recognition, ASR)领域, 如面向电话交谈的语音识别系统中, 统计语言模型(Language model, LM)存在着严重的数据稀疏问题. 本文提出了一种基于等概率事件的采样语料生成算法, 自动生成领域相关的语料, 用来强化统计语言模型建模. 实验结果表明, 加入本算法生成的采样语料可以缓解语言模型的稀疏性, 从而提升整个语音识别系统的性能. 在开发集上语言模型的困惑度相对降低7.5%, 字错误率(Character error rate, CER)绝对降低0.2个点; 在测试集上语言模型的困惑度相对降低6%, 字错误率绝对降低0.4点.     

Towards identifying the roll motion parameters of a motorcycle simulator

This study aimed at identifying the roll motion parameters of a motorcycle simulator prototype. Experienced motorcyclists tuned the angular physical movement of the mock-up and that of the visual scene to achieve an optimal riding experience during curves. The participants exceeded the rolling angles that would be required in real-world riding, while avoiding leaning the mock-up beyond 10°. In addition, they were more influenced by the speed of the virtual motorcycle than by road curvature, especially in a wide field of view. Heterogeneity was found in the roll applied to the visual scene. The overall patterns suggest that at least when washout is not applied to remove the side forces that in real-world riding are compensated by a centrifugal force, greater roll of the visual at the expense of the mock-up is mandatory to avoid performance biases that might be enhanced due to fear of falling off the simulator. Future roll motion models must take into consideration factors such as riding postures, which might not only influence the forces operating on the rider-motorcycle system, but also how motorcyclists perceive the visual world.     

A heuristic approach to selecting views for materialization

XML data warehouses are becoming more popular as data is harvested from the web or as output from web services. As these warehouses tend to grow significantly over time, various techniques for expediting queries have been developed. One such technique is to materialize some or all of the queries in advance of query processing. These views are then subject to change either when underlying data changes or view definitions themselves are modified by users. The work in this paper focuses on changes to view definitions or view adaptation as it is known. Our approach is to segment the materialized view into fragments to minimize the effect of view changes. One crucial aspect to this approach is how to select the best fragments for materialization. In this paper, we introduce a new approach to selecting fragments based on heuristics derived from costs associated with the view graph. Copyright © 2013 John Wiley & Sons, Ltd.     

Examining the role of perceived value in virtual communities continuance: its antecedents and the influence of experience

Although perceived value has long been recognised as an influential means of affecting continuance intention in information systems (IS), little attention has been devoted to explore its antecedents, which constitutes an important research issue. This study, building on prior literature on continued usage in IS as well as the resource-based view, proposed a model to address this gap. Our model suggests that perceived value, a major driving force for members’ satisfaction and continuance intention, is affected by four kinds of resources embedded in virtual communities, which are relationship resources, technology infrastructure, knowledge resources and human resources. To provide additional insights on the pivotal role of perceived value, we also postulate that experience moderates the link between perceived value and its antecedents. Data collected from 235 members of a professional virtual community provide strong support for the research model. It was found that perceived value exerts a great effect on both satisfaction and continuance intention. In addition, when different levels of experience are taken into consideration, relationship resources, knowledge resources and human resources were found to be more salient to high-experience members, whereas technology infrastructure was found to be more salient to low-experience members. Finally, this study discusses the implications of these findings and offers direction for future research.     

Continuous Self‐Collision Detection for Deformable Surfaces Interacting with Solid Models

In this paper, we propose a new continuous self‐collision detection (CSCD) method for a deformable surface that interacts with a simple solid model. The method is developed based on the radial‐view‐based culling method. Our method is suitable for the deformable surface that has large contact region with the solid model. The deformable surface may consist of small round‐shaped holes. At the pre‐processing stage, the holes of the deformable surface are filled with ghost triangles so as to make the mesh of the deformable surface watertight. An observer primitive (i.e. a point or a line segment) is computed so that it lies inside the solid model. At the runtime stage, the orientations of triangles with respect to the observer primitive are evaluated. The collision status of the deformable surface is then determined. We evaluated our method for several animations including virtual garments. Experimental results show that our method improves the process of CSCD.     

Characterizing image quality of autostereoscopic displays by using the maximum luminance at each viewing position

A metric of the 3D image quality of autostereoscopic displays based on optical measurements is proposed. This metric uses each view's luminance contrast, which is defined as the ratio of maximum luminance at each viewing position to total luminance at that position. Conventional metrics of the autostereoscopic display based on crosstalk, which uses “wanted” and “unwanted” lights. However, in case of the multiple‐views‐type autostereoscopic displays, it is difficult to distinguish exactly which lights are wanted lights and which are unwanted lights. This paper assumes that the wanted light has a maximum luminance at the good stereoscopic viewing position, and the unwanted light also has a maximum luminance at the worst pseudo‐stereoscopic viewing position. By using the maximum luminance that is indexed by view number of the autostereoscopic display, the proposed method enables characterizing stereoscopic viewing conditions without using wanted/unwanted light. A 3D image quality metric called “stereo luminance contrast,” the average of both eyes' contrast, is proposed. The effectiveness of the proposed metric is confirmed by the results of optical measurement analyses of different types of autostereoscopic displays, such as the two‐view, scan‐backlight, multi‐view, and integral.     

Information systems use as strategy practice: A multi-dimensional view of strategic information system implementation and use

Information systems (IS) are strategic in so far as they are used to realize strategic intent. Yet, while much has been said about aligning IS functionality with the strategic intent and how to organizationally implement strategically aligned systems, less is known of how to successfully implement strategic change associated with system use – a truly critical challenge within strategic IS implementation. Drawing on a strategy-as-practice perspective we address this gap by developing a multi-dimensional view of IS strategy, conceptualizing three key challenges in the IS strategy process, to explain how and why a paper mill, despite successfully implementing a strategic production management system, failed to produce intended strategic change. We call this outcome strategy blindness: organizational incapability to realize the strategic intent of implemented, available system capabilities. Using a longitudinal case study we investigate how cognitive rigidity of key actors and fixed, interrelated practices shaped the implementation of the new production system. We also identify core components and dynamics that constitute a richer multi-dimensional view of the IS strategy implementation (alignment) process. In particular, we identify three salient factors that contribute to strategy blindness – mistranslation of intent, flexibility of the IT artifact and cognitive entrenchment – and discuss how they affect strategic implementation processes. We conclude by discussing implications of our findings for IS strategy theory and practice, especially the contribution of strategy-as-practice to this stream of research.     

The study on the conductivity of styrene-maleic anhydride copolymer electrolytes based on poly(ethylene glycol)400 and LiClO4

Polyelectrolytes, in this study were synthesized from styrene-maleic anhydride (SMA) copolymer, poly(ethylene glycol)400 (PEG400), and lithium perchlorate (LiClO₄). Fourier transform infrared spectroscopy (FTIR), and magic angle spinning (MAS) solid-state NMR were used to monitor the interaction between Li⁺ ions and polymer. The results of FTIR and MAS solid-state NMR indicate the Li⁺ ions are preferentially coordinated to the ether oxygen of PEG. The T_g of the PEG segments in polyelectrolyte increases with LiClO₄ concentration, as determined by differential scanning calorimetry (DSC), indicating that solubility of the Li⁺ ions in the host polymer increases with the PEG content. Impedance spectroscopy (IS) shows that the bulk conductivity of polyelectrolytes and the conductivity behavior obeys the Vogel-Tamman-Fulcher (VTF) equation.