包装材料学课程建设的实践

北京印刷学院包装材料学课程建设的实践证明,要培养创新型包装人才,就要加强课程建设。而本课程建设的途径在于,一是要拓展课程专业知识,二是强化实践教学环节,三是重视教材建设,四是加强实训教学,五是突出教学改革与教学研究,六是建立一支合理的教学队伍。     

Structured fault tree synthesis based on system decomposition

The purpose of this article is to explain how to decompose a system so that its fault trees can be synthesized more efficiently and in a structured and recursive manner. Under such a decomposition, modules such as control/trip loops will be regarded as dummy units at first so that the system size can be reduced significantly and dramatically. The fault tree of a top event can thus be constructed as follows: the one for the reduced system is synthesized first and then each of its terminal events, when these are events of a dummy unit, will be further developed. In order to carry out such a synthesis automatically, each dummy unit must be tried first, in order to be standardized, so that its unit-model can be established, and then saved in a database in advance. A suitable system input format must also be designed so that the fault tree can be synthesized automatically simply by keying-in the top event and the system.     

On the concepts of admissibility and coherence

In the present paper it will be argued that if a parameter value assigns zero probability to an open set containing the actual response, then that parameter value should be excluded from the parameter space. When this is done, the model becomes a restricted model, and sampling theory inferences should be focused on the sampling distribution of an hypothetical independent response from the restricted model. The above situation may arise when probability densities vanish outside a compact set. This phenomenon arises frequently in the real world, but it is usually ignored for reasons of mathematical convenience. Although many statistical procedures remain substantially the same when we consider this restricted model, admissibility propertics may be drastically changed, and inferences which are known to be inadmissible may turn out to be really admissible. Thus, Stein's phenomenon concerning the inadmissibility of the sample mean as an estimator of the population mean of ap-variate normal distribution whenp≥3may be explained by the fact that the distribution has a compact support but this has been ignored by reasons of mathematical convenience. The introduction of a restricted model is also important in the study of coherence. Thus, it will be shown that Brunk's theory of countably additive coherence, which admits the use of countably additive improper priors, can be improved with the introduction of a restricted model. Thus, the theory will be unified because it will be proved that the posterior is really coherent if and only if it is a Bayes posterior, and it will be simplified because it will not be required that the prior be minimally compatible with the model.     

基于主动防御的网络安全基础设施可信技术保障体系

本文介绍了网络安全基础设施可信保障体系建设的现状、问题及未来构建策略。通过对现有安全保障体系建设现状和存在问题的剖析,提出我国网络安全基础设施亟须构建基于主动防御思想的可信技术保障体系。为此,提出可信技术保障体系建设策略建议,主要包括:以自主创新的主动防御计算体系结构作为构建可信技术保障体系的突破点;在落实信息安全系统国产化的战略合作中一定要真正形成实质的本土化;加大自主创新力度,推动主动防御的理论研究、产品研发和工程应用;积极推进可信计算标准的制定和推广应用工作,以推动可信技术保障体系的规范化发展,开展试点示范。     

外科植入物用不锈钢金相试样的制备

对外科植入物不锈钢试样的制备进行了试验。结果表明，牙托树脂具有最佳的凝固速度和可填充性，可用手捏成任意的形状，使试样可任意地被压入或被包住，可做到试样镶嵌的随意性，尤其适合细丝和薄板的镶嵌；试面抛光选用非压敏胶植绒型抛光布，抛光效果好，可准确评定夹杂物；选用王水做侵蚀试剂，用擦拭的方法可有效地显示游离铁素体和其显微组织。     

Study on Training Innovation Ability of Forestry and Agricultural Mechanical Post-graduates

For training forestry and agricultural mechanical post-graduates' innovation ability. This paper studied some problems hindering students improvement,mean value and standard deviation of time management tendency of students were researched. The results showed,graduate enthusiasm should be mobilized,curriculum should be optimized,new teaching methods should be introduced,practice should be strengthened and paid more attention,a strict system of management and evaluation should be established.     

从失效案例探讨钢制紧固件的氢脆问题

讨论了影响钢制紧固件氢脆敏感性的主要因素。分析认为,设计上要充分考虑材料强度对氢脆敏感性的影响,尽量降低其强度水平;要采用合适的热处理工艺,以减少晶界脆化元素,抑制薄膜状碳化物的形成,从而获得氢脆敏感性小的显微组织;在加工及装配过程中,应尽可能避免在零件表面产生机械损伤;要采用低氢脆电镀工艺,必要时采用无氢脆的达克罗等涂覆方法;电镀后要采用合理的除氢工艺,进行严格除氢处理;对于重复使用件,在酸洗去除镀层后要先进行除氢处理,然后电镀,再除氢。     

预拉力设计值对抗滑移系数试验的影响

采用不同的预拉力值进行抗滑移系数试验,在测得滑移载荷值后,进行了抗滑移系数的计算。通过数据比较可以得出：采用高强度螺栓材料本身的实际抗拉强度计算得出预拉力值,可以避免采用不同标准规定值导致预拉力各异的问题,并在一定程度上充分发掘了螺栓材料的最佳性能,从而提高了抗滑移系数试验的合格率。     

Soliton interactions in dispersion-decreasing fibers with the exponential dispersion profile

In this paper, soliton interactions in dispersion-decreasing fibers with the exponential dispersion profile will be investigated. Analytic two-soliton solutions will be obtained with Hirota’s method. With the different dispersion profile of dispersion-decreasing fibers, the propagation characteristics of solitons will be exhibited, and some soliton properties will be adjusted. Results presented in this paper could be used in soliton control in the dispersion-decreasing fibers.     

Two Layer Symmetric Cryptography Algorithm for Protecting Data fromAttacks

Many organizations have insisted on protecting the cloud server from the outside, although the risks of attacking the cloud server are mostly from the inside. There are many algorithms designed to protect the cloud server from attacks that have been able to protect the cloud server attacks. Still, the attackers have designed even better mechanisms to break these security algorithms. Cloud cryptography is the best data protection algorithm that exchanges data between authentic users. In this article, one symmetric cryptography algorithm will be designed to secure cloud server data, used to send and receive cloud server data securely. A double encryption algorithm will be implemented to send data in a secure format. First, the XOR function will be applied to plain text, and then salt technique will be used. Finally, a reversing mechanism will be implemented on that data to provide more data security. To decrypt data, the cipher text will be reversed, salt will be removed, and XOR will be implemented. At the end of the paper, the proposed algorithm will be compared with other algorithms, and it will conclude how much better the existing algorithm is than other algorithms.     

CT系统空间分辨率测量技术的改进

调制传递函数反映了CT系统的空间分辨率,可通过点扩展函数（PSF）,边缘响应函数（ERF）进行计算。对PSF和ERF方法分别进行改进。在PSF方法中,通过图像处理分割出点扩展区域,点扩展区域呈圆形,从而可以利用数学变换的方法找出中心点位置,并计算出MTF曲线。在ERF方法中,通过图像处理分割出体模图片中的目标线,然后对目标线进行直线拟合,再利用数学变换计算出拟合直线与垂直位置的偏移角度,从而进行相应角度的旋转。可以使ERF数据相互对应,从而直接进行平均处理。实验结果表明提出的改进方法是准确和有效的,简化了临床扫描条件,为CT系统的评估带来方便。     

Reflection on Development Strategy of Engineering Management Discipline in China

A large number of engineering management professionals are required to promote engineering management efficiency, but the existing engineering management training system has some gaps with economical and social development in China. Development of engineering management discipline has very important strategic significance in China. This paper explores the disciplinary characteristics of engineering management, and analyzes the developmental issues about education of engineering management discipline. Meanwhile, the paper also proposes that the construction for development strategy of China’s engineering management discipline should be accelerated in the following aspects: Theoretical system of engineering management must be built and methodology of engineering management needs to be explored and perfected; advantages of various universities should be fully expressed, to show their own characteristics with accurate and reasonable positioning; knowledge system of engineering management discipline must be organized and integrated; practical ability of engineering management professionals needs to be promoted; education level of engineering management discipline should be perfected and training objectives at various levels must be clarified; teaching methods and means have to be reformed.     

High speed ground transportation: Some current and future alternatives

High-speed transportation, the value of time, and the social and technological considerations of inter-city transportation will be discussed in this article. A particularly promising mode of high-speed ground transportation (MAGLEV) will be discussed in some detail. An average speed for HSGT service, 400 kilometers per hour, seems to be attainable for reasons that will be set forth. In conclusion, the proposal for a “hypersonic” subway will be analyzed.     

Synthesis, Growth Mechanism, and Applications of Zinc Oxide Nanomaterials

This article reviews recent progresses in growth mechanism, synthesis, and applications of zinc oxide nano-materials （mainly focusing on one-dimensional （1D） nanomaterials）. In the first part of this article, we briefly introduce the importance, the synthesis methods and growth mechanisms, the properties and applications of ZnO 1D nanomaterials. In the second part of this article, the growth mechanisms of ZnO 1D nanomaterials will be discussed in detail in the framework of vapor-liquid-solid （VLS）, vapor-solid （VS）, and aqueous solution growth （ASG） approaches. Both qualitative and quantitative information will be provided to show how a controlled synthesis of ZnO 1D nanomaterials can be achieved. In the third part of this article, we present recent progresses in our group for the synthesis of ZnO 1D nanomaterials, and the results from other groups will only be mentioned briefly. Especially, experiment designing according to theories will be elaborated to demonstrate the concept of controlled synthesis. In the fourth part of this article, the properties and potential applications of ZnO 1D nanomaterials will be treated. Finally, a summary part will be presented in the fifth section. The future trend of research for ZnO 1D nanomaterials will be pointed out and key issues to be solved will be proposed.     

调节阀振动特征的研究进展

为全面认识调节阀振动问题,以近年国内工程领域调节阀振动事故案例为引,从外激振动和流激振动两个方面分析了调节阀振动产生机理,从实验方法、理论模型仿真和数值模拟三个角度总结了调节阀振动研究方法,从根源减振与传播减振两种类型回顾了调节阀振动抑制措施。经过分析总结,探讨了目前研究存在的主要问题,并给出了展望:流激振动机理研究还不够完善,不同类型的流激振动无法区分,应建立特征识别技术,并开展竞争机制研究;实验方法与理论模型仿真各有局限,有待提高。不同数值模拟方法的准确性与资源消耗比较有待探索;应建立调节阀品位评价体系,对高品位调节阀开发根源减振措施,对低品位调节阀选用传播减振措施。     

Analytic diffraction analysis of a 32-m telescope with hexagonal segments for high-contrast imaging

Large segmented telescopes cannot be modeled accurately with fast-Fourier-transform techniques since small features such as gaps between the segments will be inadequately sampled. An analytic Fourier-transform method can be used to model any pupil configuration with straight edges, including tolerance analysis and some types of apodization. We analytically investigated a 32-m segmented primary with 18 hexagonal segments for high-contrast imaging. There are significant regions in the image in which extrasolar planets could be detected. However, the hexagonal profile of the pupil was not as useful as expected. The gaps between the segments, the secondary obscuration, and the secondary spiders must be as small as possible and their edges must be apodized. Apodizing the edges of the individual segments reduced the useful regions in the image since the gaps appeared to be wider.     

Colour Transparencies on Coloured Supports

When transparencies are to be viewed by light, the colour of which does not appear to be perfectly white, pictures of better quality can be obtained by coating the film on coloured base; in the case of transparencies to be viewed by tungsten-light projectors the base would be coloured bluish. By making the base coloured instead of having image layers which produce coloured gray scales, consistency of perceived colour balance can be achieved at the lowest densities as well as at other densities. Reduced halation and less edge-fog for those colours absorbed by the base colour are additional advantages.     

大型锌锭铸模结构与参数对其应力场的影响

以降低大型锌锭模的热应力、延长其使用寿命为目的,本文采用有限元方法,分析了散热筋、壁厚、圆角半径、上部法兰等结构与参数条件对铸模应力场的影响.计算结果表明,通过合理配置锌锭模各部分的壁厚,可以有效地降低锌锭模上部应力,防止裂纹产生.此外锌锭模结构不宜采用散热筋,应采用较大的圆角半径,上部不宜设置法兰.本文研究结果可作为大型锌锭、铝锭等模具设计制造的理论参考.     

Improving the quality of aluminium diecastings by novel techniques

Conventional liquid metal diecasting entraps air and produces porous diecastings which cannot be heat treated without distortion. Processes will be described for the diecasting of semi-solid alloys which are produced in a thixotropic condition. Such alloys can be handled as if a rather soft solid but, when sheared in a diecasting machine, will flow like a somewhat viscous liquid. Because the alloy can be handled as a solid, metal billet handling equipment can be used and die design simplified. Because the alloy is forced into the die as a slurry, less turbulence occurs and sound diecastings can be produced. The lower temperatures used mean that half the latent heat has been removed and so lower die temperatures result in leses thermal shock and faster cycle times, thus improving the productivity of the diecasting process. The absence of porosity allows heat treatment operations to be carried out without distortion to provide castings with strengths approaching those of forgings. Methods of carrying this out will be described and examples shown.     

中国绿色包装的成就、问题及对策（下）

中国发展绿色包装取得了可喜的成就。但存在缺乏包装废弃物回收再利用法规、缺乏规范性的废资源回收利用网络、缺乏回收再利用产业等问题。因此,必须实行绿色包装发展＂两步走＂策略,迅速制定国家层面的法规和标准,扶持发展各类可降解包装材料及环保型包装辅助材料的研发及生产,高度重视包装机械的科技研发,把产品创新放在首位,并制定中国绿色包装工程＂十二五＂发展规划,以推进绿色包装的发展。