National and international publishers have been depositing digital publications at the National Library of the Netherlands (KB) since 2003. Until recently, most of these publications were deposited in the Portable Doc...National and international publishers have been depositing digital publications at the National Library of the Netherlands (KB) since 2003. Until recently, most of these publications were deposited in the Portable Document Format. New projects, for example the Web archiving project, force the KB to handle more heterogeneous material. Therefore, the KB has developed a quantifiable file format risk assessment method. This method can be used to define digital preservation strategies for specific file formats. The choice for a specific file format at creation time or later in the life cycle of a digital object influences the long-term access to the digital object. The evaluation method contains seven sustainability criteria for file formats that are weighed for importance. There seems to be consensus on the sustainability criteria. However, as the weighing of these criteria is connected to an institution's policy, the KB wonders whether agreement on the relative importance of the criteria can be reached at all. With this paper, the KB hopes to inspire other cultural heritage institutions to define their own quantifiable file format evaluation method.展开更多
In this hard disk record system, the IDE hard disk is controlled by FPGA(Field Programmable Gate Array), and the image is recorded to file format directly. In the same time, the recorded image is real-time and lossles...In this hard disk record system, the IDE hard disk is controlled by FPGA(Field Programmable Gate Array), and the image is recorded to file format directly. In the same time, the recorded image is real-time and lossless. All of this is convenient for subsequent processing.展开更多
目的嵌入式数字视频录像机(digital video recorder,DVR)系统中的多媒体(视频/音频)数据往往是电子数据司法鉴定领域的重要证据,然而在司法鉴定实践中,DVR被意外删除、恶意删除或遭受损坏导致DVR中数据无法访问的现象屡见不鲜,这无疑使...目的嵌入式数字视频录像机(digital video recorder,DVR)系统中的多媒体(视频/音频)数据往往是电子数据司法鉴定领域的重要证据,然而在司法鉴定实践中,DVR被意外删除、恶意删除或遭受损坏导致DVR中数据无法访问的现象屡见不鲜,这无疑使得电子数据鉴定过程变得更加困难。方法结合司法鉴定工作实务,主要以存储于Micro SD卡中无法访问的DVR视频文件为例,开展了基于文件分配表(file allocation table,FAT)32文件系统和H.264相关文件格式的DVR数据恢复研究。结果通过探讨的两种方法恢复的视频文件可以正常访问,同时还可通过运行脚本文件实现DBR的自动重建。结论探讨的两种方法可有效恢复FAT32文件系统的DVR数据和H.264格式的DVR数据。此外,通过运行脚本文件自动重构DBR,可有效提高司法鉴定效率。相关鉴定技术的研究对嵌入式DVR视频的鉴定技术研究具有重要的理论研究意义和实践应用价值。展开更多
A casting process CAD is put forward to design and draw casting process. The 2D casting process CAD, most of the current systems are developed based on one certain version of the AutoCAD system. However the applicatio...A casting process CAD is put forward to design and draw casting process. The 2D casting process CAD, most of the current systems are developed based on one certain version of the AutoCAD system. However the application of these 2D casting process CAD systems in foundry enterprises are restricted because they have several deficiencies, such as being overly dependent on the AutoCAD system, and some part files based on PDF format can not be opened directly. To overcome these deficiencies, for the first time an innovative 2D casting process CAD system based on PDF and image format file has been proposed, which breaks through the traditional research and application notion of the 2D casting process CAD system based on AutoCAD. Several key technologies of this system such as coordinate transformation, CAD interactive drawing, file storage, PDF and image format files display, and image recognition technologies were described in detail. A practical 2D CAD casting process system named HZCAD2D(PDF) was developed, which is capable of designing and drawing the casting process on the part drawing based on the PDF format directly, without spending time on drawing the part produced by AutoCAD system. Finally, taking two actual castings as examples, the casting processes were drawn using this system, demonstrating that this system can significantly shorten the cycle of casting process designing.展开更多
文摘National and international publishers have been depositing digital publications at the National Library of the Netherlands (KB) since 2003. Until recently, most of these publications were deposited in the Portable Document Format. New projects, for example the Web archiving project, force the KB to handle more heterogeneous material. Therefore, the KB has developed a quantifiable file format risk assessment method. This method can be used to define digital preservation strategies for specific file formats. The choice for a specific file format at creation time or later in the life cycle of a digital object influences the long-term access to the digital object. The evaluation method contains seven sustainability criteria for file formats that are weighed for importance. There seems to be consensus on the sustainability criteria. However, as the weighing of these criteria is connected to an institution's policy, the KB wonders whether agreement on the relative importance of the criteria can be reached at all. With this paper, the KB hopes to inspire other cultural heritage institutions to define their own quantifiable file format evaluation method.
文摘In this hard disk record system, the IDE hard disk is controlled by FPGA(Field Programmable Gate Array), and the image is recorded to file format directly. In the same time, the recorded image is real-time and lossless. All of this is convenient for subsequent processing.
基金financially supported by the Program for New Century Excellent Talents in University (No.NCET-09-0396)the National Science&Technology Key Projects of Numerical Control (No.2012ZX04012-011)the Fundamental Research Funds for the Central Universities (2014-IV-016)
文摘A casting process CAD is put forward to design and draw casting process. The 2D casting process CAD, most of the current systems are developed based on one certain version of the AutoCAD system. However the application of these 2D casting process CAD systems in foundry enterprises are restricted because they have several deficiencies, such as being overly dependent on the AutoCAD system, and some part files based on PDF format can not be opened directly. To overcome these deficiencies, for the first time an innovative 2D casting process CAD system based on PDF and image format file has been proposed, which breaks through the traditional research and application notion of the 2D casting process CAD system based on AutoCAD. Several key technologies of this system such as coordinate transformation, CAD interactive drawing, file storage, PDF and image format files display, and image recognition technologies were described in detail. A practical 2D CAD casting process system named HZCAD2D(PDF) was developed, which is capable of designing and drawing the casting process on the part drawing based on the PDF format directly, without spending time on drawing the part produced by AutoCAD system. Finally, taking two actual castings as examples, the casting processes were drawn using this system, demonstrating that this system can significantly shorten the cycle of casting process designing.
