Chaotic tags and asynchronous data transmission

A method to identify entities by means of tags is suggested. The tags are represented by sets of unstable periodic orbits that form the framework of a chaotic attractor. The method is applied to asynchronous packet data transmission from a number of users over a shared channel. Experimental transmission of two musical signals is reported.     

Evidence for a silicon oxycarbide phase in the Nicalon silicon carbide fibre

The Nicalon silicon carbide fibre has been studied by X-ray photoelectron spectroscopy. Elements entering the fibre are carbon, silicon and oxygen. In addition to previously reported chemical entities (silicon carbide, silica and graphitic carbon) evidence is found of the presence of a new supplementary phase which is attributed to an intermediate silicon oxycarbide phase. As this phase is found to participate in very appreciable proportions to the composition of the fibre, some influence on the properties of this fibre can be anticipated.     

Microstructure and mechanical properties of nanocrystalline high strength Al–Mg–Si (AA6061) alloy by high energy ball milling and spark plasma sintering

In the present paper, the microstructure and mechanical properties of nanostructured Al–Mg–Si based AA6061 alloy obtained by high energy ball milling and spark plasma sintering were reported. Gas atomized microcrystalline powder of AA6061 alloy was ball milled under wet condition at room temperature to obtain nanocrystalline powder with grain size of 30 nm. The nanocrystalline powder was consolidated to fully dense compacts by spark plasma sintering (SPS) at 500 °C. The grain size after SPS consolidation was found to be 85 nm. The resultant SPS compacts exhibited microhardness of 190–200 HV_100 g, compressive strength of 800 MPa and strain to fracture of 15%.     

AutoCAD与ParaSolid三维边界模型信息直接交换

对ACIS和ParaSolid的三维实体边界表达数据结构进行分析,基于DwgDirect接口技术,直接打开AutoCAD的DWG文件,对AutoCAD的DWG文件中基于ACIS的三维实体边界信息遍历,获取实体边界的拓扑信息和几何信息;基于ParaSolid提供的API开发函数,通过实体拓扑构造、实体几何构造和几何与拓扑附属关联,实现AutoCAD与ParaSolid三维边界模型的直接交换。最后给出一个直接交换实例。     

AutoCAD标注组元信息自动提取的研究

论述了通过编程自动提取AutoCAD中尺寸、引线和公差标注等基本图元信息的方法.由于标注对象是一些基本图元对象构成的特定集合,其表现形式又各不相同,通过这些对象自身的属性和方法接口,无法获取重绘标注对象的足够信息,因而采用不同方式,编程自动获取构成这些标注对象的基本图形对象,进而获取这些基本图形对象中的属性信息.采用了AutoCAD的ActiveX Automation开发平台予以实现.     

GPA参加方公共采购实体性质研究

GPA文本对公共采购实体没有统一的界定,只用“政府目的”框定了采购实体的范围,致使GPA参加方在加入谈判时会对采购实体产生争议。我国自2007年启动加入GPA谈判以来,国有企业一直是各方焦灼的热点。本文通过分析美国、欧盟和韩国等GPA参加方公共采购实体的边界,并从设立依据、采用形式和政府控制这3个方面分析其共同特性,探讨了公共采购实体的法人性质,以期为我国开放政府采购市场谈判提供崭新的参考视角。     

The relation between zeolite framework structure and vibrational spectra

Using a general valence force field method, infrared and Raman spectra of pure silica zeolite crystals and molecular substructures of zeolites are calculated. Computed spectra of the substructures are directly compared with computed spectra of the crystal. Also, a comparison of the atomic displacement vectors of the vibrational modes is made. No general theoretical basis for a correlation between the presence of large structural elements and spectral features, sometimes reported, is found to exist. An extensive comparison between experimental and theoretical infrared and Raman spectra of the SiO₂ forms of sodalite and faujasite is made. Other applications of vibrational spectroscopy to zeolite structure research, such as the SiOSi angle distribution and the location of acid sites, are evaluated as well.     

Bond lengths differences between the mollusk-made and geological calcium carbonate

We used high-resolution neutron powder diffraction technique in order to accurately measure the atomic positions and bond lengths in calcium carbonates of biogenic (mollusk-made) and geological origin. As a result, in biogenic calcium carbonate we identified atomic bonds, first of all the CO bonds and some OO bonds, which obey significant modification (about 1%) with respect to those in geological calcium carbonate. Bond length changes are presumably due to the organic/inorganic interactions in natural bio-composites. Generally, the effect is more pronounced for aragonite, which is structurally more flexible (nine unfixed parameters in atomic positions) than calcite (one parameter of this kind only). The observed bond modifications can be a source of the reported changes in the frequencies of normal vibrations of the carbonate groups measured by Raman or Fourier-transform infrared spectroscopy (FTIR) techniques.     

Appropriation of space in a design office

Data from an exploratory study of space usage in a design office are reported and discussed. The argument comprises a critique of functionalist, technically utilitarian, design theory: a theory in which different groups of building users tend to be regarded as homogeneous entities. A quantitative and a qualitative analysis of the data are presented. These point to the presence among users of divergent definitions, views, of the appropriate functional bases for office layout — a factor not adequately accounted for in orthodox functional theory. In interpreting this information, reference is made to the social relations, specifically the power relations, of the groups of office personnel who express them.     

Low-pressure-plasma-deposited coatings formed from mechanically alloyed powders

A limiting feature of the low-pressure-plasma-coating process at the present state of the art is the need for ?400 mesh (?37 μm) feed powder for the gun. In this study we demonstrated that mechanically alloyed MCrAltype (where M is cobalt, nickel or iron) powders suitable for low pressure plasma spraying can be prepared using the attritor process.A two-step attriting process was developed which yields a large fraction of ?400 mesh powders. A study of the effects of attritor processing parameters was made on Co29Cr6Al1Y powder that was mechanically alloyed from a blend of cobalt, chromium, CoAl and CoY powders. Coatings deposited onto IN-738 pin specimens by low pressure plasma spraying were hot corrosion tested; these compare favorably with Co29Cr6Al1Y coatings deposited using atomized powders.A three-step attriting process also was developed which is particularly useful in forming MCrAl-type powders using elemental aluminum as a starting ingredient.     

Towards a multi-disciplinary Bradford law

Bradford's law, perhaps the most well known of the Informetric regularities, analyzes the scattering of articles in a single discipline over journals. Yet journals are multi-disciplinary entities. This paper discusses the implications for Bradford's law of the multi-disciplinary character of journals, and defines a simple model that indicates the evolution of journals as a competition among subjects for space.Paper presented at the Fourth International Conference on Bibliometrics, Informetrics and Scientometrics in Berlin (Germany), September 11–15, 1993.The research reported in this paper was carried out while the author was a Fullbright fellow at the Indian Statistical Institute in Bangalore, India. The author gratefully acknowledges this support.     

采用ObjectARX 2006的多段线自动生成及编辑

将AutoCAD中的图形粘贴到Office系列软件中会导致图线宽度丢失和线宽不易调整等问题,将图线转化为多段线是解决这一问题的常用方法.论文分析了使用AutoCAD内部命令实现图线转化成多段线过程中存在的问题,给出了一种将工程图形自动转化为多段线的方法.该方法将工程图形中的图线分成开环和闭环两种,并自动识别图线类型,智能调整图线宽度,避免了手工调整过程中存在的问题,提高了效率.     

SSCM:一种语义相似度计算方法

分析了实例多重继承和实例属性层次关系对实例相似性的影响,针对原有的实例语义相似度计算方法的不足,提出了一种语义相似度计算方法SSCM,该方法综合考虑了实例多重继承关系和属性及属性值的层次关系,并利用继承关系的树状结构特点对计算过程进行了优化.实验表明,该方法在本体知识库的多种组成情况下,均能有效提高语义相似度计算的准确率.在实例多重继承关系相对复杂的情况下,准确率提高更加明显.     

基于改进几何哈希法的矢量图形检索

针对图形文件以矢量方式记录几何实体的特点,提出了一种基于改进几何哈希法的图形检索算法。与图像的对应处理方式相比,该算法充分利用图形的矢量信息,以实体基准点和实体的准确几何形式描述几何实体;在检索过程中,每个图形实体仅有基准点参与排序和查询,哈希表数据组织形式简单,查询速度快;通过验证图形实体属性,保证了查询结果的准确性。最后以矢量图形文件为图例,验证了方法的有效性。     

Polypropylene surface modification by active screen plasma nitriding

Here we describe the use of low energy plasma immersion with active screen as a convenient approach for polypropylene (PP) surface modification. Employing a stainless steel cathodic cage coated with carbon in order to prevent the sputtering of iron from the grid and its deposition onto the polymer sample, the physical chemical properties of PP surface could be effectively modified through the plasma-induced incorporation/formation of nitrogen- and oxygen-containing species. The areal densities of these elements depended on the plasma excitation source, as determined by Rutherford backscattering spectrometry (RBS). Newly formed C–O, C–N, and CO/OC–O/N–CO bonds along with C–C linkages from the PP backbone were identified at the near surface region of the specimens by X-ray photoelectron spectroscopy (XPS). The insertion of such polar reactive functionalities was further confirmed by a substantial decrease in the water contact angle upon plasma treatment. Scanning electron microscopy (SEM) analysis revealed that while no major changes in the morphology occur upon DC plasma treatments as compared to untreated samples, the use of pulsed plasma consistently leads to the formation of cracks at the surface. The herein reported approach is an attractive tool for environmental friendly low-cost surface engineering of novel materials.     

Knowledge environments representing molecular entities for the virtual physiological human

In essence, the virtual physiological human (VPH) is a multiscale representation of human physiology spanning from the molecular level via cellular processes and multicellular organization of tissues to complex organ function. The different scales of the VPH deal with different entities, relationships and processes, and in consequence the models used to describe and simulate biological functions vary significantly. Here, we describe methods and strategies to generate knowledge environments representing molecular entities that can be used for modelling the molecular scale of the VPH. Our strategy to generate knowledge environments representing molecular entities is based on the combination of information extraction from scientific text and the integration of information from biomolecular databases. We introduce @neuLink, a first prototype of an automatically generated, disease-specific knowledge environment combining biomolecular, chemical, genetic and medical information. Finally, we provide a perspective for the future implementation and use of knowledge environments representing molecular entities for the VPH.     

Determination of similar task types by the use of the multidimensional classification method: towards improving quality of working life and job satisfaction

In this paper the entity is defined as the constituent unit of the work group. Actually the entity means the individual worker, supervisor, or task. These entities have respectively their attributes and also contribute to the effectiveness of the design of the work group. Similar types of entities are constructed by considering the interrelations between attributes and effectiveness.

The suggested MDC (multidimensional classification method) is a new method of classifying the entities in relation to the defined attribute space and effectiveness space and of better constructing similar types. From the viewpoint of the operationality of design and redesign of the work group, the MDC is useful to determine rationally the similar types of entities. In fact, in relation to job satisfaction, the similar task types could be successfully constructed by the use of the MDC. As a result, higher job satisfaction could be realized by manipulating the similar task types so determined.

The similar types which are determined by the MDC are useful to create the design rules for manipulating the entities in the process of designing an effective work group. By determining the similar types of workers and supervisors and also adopting work performance and productivity as effectiveness indexes, the methodology can be established for designing an effective work group.     

在特征造型中拓扑元素命名机制的研究

特征造型中最根本的问题之一是模型的拓扑元素（面、边和顶点）经特征编辑重构模型后的识别．为此本文提出基于CSG树的拓扑标识号命名机制和虚拓扑标记号命名机制,并运用书扑元素的继承性、割裂关系表的约束准则和相似性匹配技术实现其标识号在新旧模型中正确传递,大大提高特征编辑的可靠性。