Localized construction of curved surfaces from polygon meshes: A simple and practical approach on GPU

We present a method for refining n-sided polygons on a given piecewise linear model by using local computation, where the curved polygons generated by our method interpolate the positions and normals of vertices on the input model. Firstly, we construct a Bézier curve for each silhouette edge. Secondly, we employ a new method to obtain C¹ continuous cross-tangent functions that are constructed on these silhouette curves. An important feature of our method is that the cross tangent functions are produced solely by their corresponding facet parameters. Gregory patches can therefore be locally constructed on every polygon while preserving G¹ continuity between neighboring patches. To provide a flexible shape control, several local schemes are provided to modify the cross-tangent functions so that the sharp features can be retained on the resultant models. Because of the localized construction, our method can be easily accelerated by graphics hardware and fully run on the Graphics Processing Unit (GPU).     

基于SQL-92和JDBC的SpaceOS数据库数据迁移的实现

针对Space操作系统的Postgre SQL数据库能对异构关系数据库进行数据迁移的需求,在SQL-92和JDBC基础上,介绍异构数据迁移时元数据和记录数据处理的主要流程,并设计了以表示层、元数据层、业务逻辑层和数据访问层为结构的数据迁移模块。详细分析了SQL声明前数据类型映射和代理主键值映射这两个关键步骤的算法实现。数据迁移模块在JDK1.6环境下实现。通过对异构数据库与Postgre SQL间进行数据迁移实验,验证了迁移模块是合理而有效的,具有良好的通用性和兼容性。     

pH sensor based on the crown heteropolyanion K28Li5H7P8W48O184·92H2O immobilized using a layer by layer assembly process

A new sensitive pH sensor based on immobilization of the crown heteropolyanion K₂₈Li₅H₇P₈W₄₈O₁₈₄·92H₂O (P₈W₄₈) on a electrode surface through a layer by layer assembly process is described. The immobilization is based on the electrostatic adsorption of the complex in layers of charged polyelectrolyte poly(allylamine hydrochloride) (PAH). The deposited P₈W₄₈/LBL film was investigated by cyclic voltammetry, potentiometry and electrochemical impedance spectroscopy. Compared to the electrochemical behavior of dissolved P₈W₄₈, a slight shift in the redox peak towards negative potentials is observed, which have been attributed to a slight decrease in the acidity of the interior of the P₈W₄₈/LBL film compared to the testing buffer solution. The relationship between the peak currents of the deposited P₈W₄₈/LBL film and the number of layers is shown to be linear, which demonstrates that equal amounts of P₈W₄₈ are adsorbed in each deposition layer. The P₈W₄₈/LBL modified electrode showed high sensitivities toward pH. Therefore, such electrodes were tested as pH sensors using the titration method. The resulting pH sensor has a detection range of pH 1–13, a sensitivity of 69 ± 2 mV/pH, high repeatability (<3 mV), fast response time (<7 s), low sensitivity toward change in ionic strength and nature of the supporting electrolyte, low internal resistance and a working life time of at least 3 months. Moreover, the sensor is easy to manufacture and can be easily miniaturized for measurements in micro- and nano-systems.     

Effect of multiaxial stress state on creep damage in ASME T92 welded joint

This study reports the type IV fracture process and the influence of multiaxial stress state in ASME T92 welded joints during creep. The type IV fracture occurs at the fine‐grained heat‐affected zone (ie, FGHAZ), involving void initiation, growth, and coalescence, microcrack occurrence, propagation and extension, and eventual macrocrack with consequent joint failure. The creep damage is not uniformly distributed along the thickness direction in the FGHAZ, and the central part of the welded joint is the most seriously damaged region. The equivalent creep strain is higher at the external surface, but the stress triaxiality is larger in the centre section. Large equivalent creep strain could promote creep void initiation, whereas high hydrostatic pressure and stress triaxiality factor accelerate void growth in the FGHAZ of T92 joints. Besides, reducing groove angle and HAZ width of the joints is recommended to delay the occurrence of type IV cracking because of lower equivalent creep strain and stress triaxiality factor.     

Hot corrosion behavior of TiO2 doped,Yb2O3 stabilized zirconia exposed to V2O5 + Na2SO4 molten salt at 700–1000 °C

3.5 mol% Yb₂O₃ stabilized zirconia (YbSZ) doped with 10 mol% TiO₂ (Ti-YbSZ) was produced, and its hot corrosion behavior exposed to Na₂SO₄ + V₂O₅ molten salt was investigated. The as-fabricated ceramic mainly consists of metastable tetragonal (t′) phase. When exposed to the molten salt at 700 °C, 800 °C, 900 °C and 1000 °C for 2 h and 10 h, YbVO₄ and m-ZrO₂ formed as corrosion products due to chemical reactions between the ceramics and the salt. Ti⁴⁺ in Ti-YbSZ solid solution keeps stable during the hot corrosion tests, which acts as a stabilizer for ZrO₂, preventing total decomposition of the t′ phase. After the hot corrosion tests, Ti-YbSZ has an apparently lower m phase content than Y₂O₃ doped Zirconia and YbSZ, indicative of better corrosion resistance. The hot corrosion mechanism of Ti-YbSZ is proposed based on Lewis acid-base rule, phase diagrams and thermodynamics.     

实际量子保密系统中偏振漂移对截听重发攻击的影响

研究了有偏振漂移的量子保密系统中的截听重发攻击问题.利用二维模型刻画密钥分发的过程.通过模型分析和研究计算,得到了合法通信者以及窃听者之间的关系式,掌握了系统的探测效率损耗,以及量子误码率的波动范围.筛后数据的互信息量显示,相比BB84协议,B92协议的互信息量低,这是由于B92协议将协议所用的量子态简化为两态所付出的代价.窃听者获取的信息可能多于合法通信者得到的信息,这也将威胁密钥产生的保密性.     

Ports and the local embedding of commodity flows

Empirical evidence remains lacking about the territorial embedding of material flows. An analysis of 189 port regions in advanced economic areas (Europe, Japan, and the United States), validates a number of ideas proposed by regional science and transport geography. Core economic regions such as large urban tertiary centres concentrate most valued, diversified, and weighty traffic, while more peripheral and traditional ones tend to specialize in bulky traffic. Moreover, the level of industry relatedness of port traffic appears as a key component of the socio‐economic wealth of port regions. The research also underlines noticeable linkages between types of port regions and types of port‐related policies across the three studied areas.     

Modernist Photography and Women’s Social Networks: The Case of Olive Cotton and Margaret Michaelis

This article’s title refers to the larger project of illuminating the social networks informing Australian artistic communities from the late colonial period to the middle of the twentieth century. Focusing primarily on developments in photography, the article itself asks what were the links between creative practices and the social relationships that characterised the modernist period in particular? It attempts to answer this question by examining the relationship between two retrospectively celebrated women photographers working in the war years in Australia – Olive Cotton and Margaret Michaelis. For a fair portion of their lives Cotton and Michaelis lived in the same city, worked contemporaneously in the relatively small field of studio photography, and shared similar artistic and commercial ambitions, yet they had virtually no professional or personal contact with each other. There is some evidence to suggest that social networks played a role in training early Australian women photographers, particularly those working in the professional studio system between the 1890s and the 1920s. Social networks would take on an explicitly political role in the consciousness-raising feminist context of women’s photography in Australia from the 1970s to the 1990s. Given that Cotton and Michaelis were professional photographers during the interval between these periods, one is bound to ask whether their lack of contact had a personal basis or there was a wider more socially determined reason. In other words, was there something about the social conditions effecting Australia’s artistic associations at this time that explains the lack of artistic connections between women, and if so was this lack the same across all the arts or particularly pronounced in photography?     

Microstructures and high-temperature mechanical properties in 9Cr–0.5Mo–1.8W–VNb steel after aging at 650°C

A series of experiments, including post-aged tensile tests, charpy impact tests, Vickers hardness test, scanning electron microscopy (SEM) examinations and transmission electron microscopy (TEM) observations, were carried out to investigate the microstructure evolution and high-temperature mechanical properties of P92 steel. Experimental results show that martensitic lath structure gradually recovers during long-term aging; meanwhile, the content and size of spheroidal M₂₃C₆ together with Laves phase distributed mainly along prior austenite grain boundaries and subgrain boundaries increase with extending the aging time, but MX in grain interior seems to be stable. The strength parameters (σ_ys and σ_ult), the ductile parameters (δ and Φ_f) and high-temperature impact absorbed energy all show an initially slight increase followed by a decrease with the increase of the aging time up to 500?h. After aging for 2000?h at 650°C, this degradation behaviour becomes stable, although the Vickers hardness is not strongly affected by the aging time. Based on the microstructural observations and high-temperature mechanical properties, the strengthening mechanism of P92 steel was discussed.     

T92钢时效硬度变化试验及蠕变寿命预测研究

硬度是衡量材料部件老化的一个重要指标，针对T92铁素体钢高温时效后的硬度变化做了详细的试验分析研究，归纳了硬度变化的原因，还对硬度法评估蠕变寿命进行了探讨，并结合试验数据，根据硬度法外推了T92钢的蠕变寿命。