Model Selection for Unsupervised Learning of Visual Context

This study addresses the problem of choosing the most suitable probabilistic model selection criterion for unsupervised learning of visual context of a dynamic scene using mixture models. A rectified Bayesian Information Criterion (BICr) and a Completed Likelihood Akaike’s Information Criterion (CL-AIC) are formulated to estimate the optimal model order (complexity) for a given visual scene. Both criteria are designed to overcome poor model selection by existing popular criteria when the data sample size varies from small to large and the true mixture distribution kernel functions differ from the assumed ones. Extensive experiments on learning visual context for dynamic scene modelling are carried out to demonstrate the effectiveness of BICr and CL-AIC, compared to that of existing popular model selection criteria including BIC, AIC and Integrated Completed Likelihood (ICL). Our study suggests that for learning visual context using a mixture model, BICr is the most appropriate criterion given sparse data, while CL-AIC should be chosen given moderate or large data sample sizes.     

一种可替代漂珠的低密度材料

漂珠低密度水泥浆由于密度低、强度高、体系稳定而在油田低压易漏层及低压油气层长封固段固井作业中获得了广泛的应用。但近年来,由于漂珠的产量越来越少,油田低成本要求急需开发代替漂珠的新型减轻材料,以满足配制低密度水泥浆的需求。开发了BCL-10S低密度混合减轻材料,其物化性能与漂珠相当,用它作减轻剂配制的低密度水泥浆性能与用漂珠作减轻剂配制的低密度水泥浆性能相媲美,并已经在长庆油田获得了应用。     

Multiple Scan Chain Design for Two-Pattern Testing

Non-standard fault models often require the application of two-pattern testing. A fully-automated approach for generating a multiple scan chain-based architecture is presented so that two-pattern test sets generated for the combinational core can be applied to the sequential circuit. Test time and area overhead constraints are considered.     

湘中海相浅层湘冷1井酸压工艺研究及应用

湘冷1井具有气层埋藏浅（400m-500m）、纵向上裂隙发育的特点，属低孔、低渗的含泥质灰岩致密储层。大量室内实验和研究采用“前置液酸压＋闭合酸化”工艺技术，并优选了相应降阻酸和闭合酸配方。通过酸压实现了该井工业油气流的突破，取得了明显的增产效果，为新区海相浅层气的开发探索出了一套成熟的改造增产措施。     

高温旋风除尘器的设计

在PTA(精对苯二甲酸)的生产过程中,工艺废气经尾气膨胀透平机降压后进入RTO蓄热式焚烧炉将有毒有害的有机物焚烧分解后排入大气,为了达到粉尘的排放标准(小于120mg/m~3),在焚烧炉之后加上这台高温烟气除尘器,废气经除尘后达到了排放标准,而且最大程度地减少了热量损失,实践证明此项改造是成功的。文章探讨如何进行高温烟气除尘器的设计,并介绍了高温多管陶瓷旋风烟气除尘器的结构。     

低阻VDMOSFET的优化设计与制造

文章对9926型双N沟增强型VDMOSFET进行了结构和版图的优化设计。给出了该器件的纵横向结构参数,材料的物理参数和版图总体结构。单胞结构的优化设计使单胞密度达到204万个/cm2,比国际市场现有产品的单胞密度(156万个/cm2)提高了30%。这种设计采用浅n+注入工艺可使器件生产成本下降31%。最后对研制结果进行了分析讨论。     

我国建筑石油沥青标准的沿革及现状

论述了我国建筑沥青标准的变化历程及现状,对我国建筑沥青的生产、产品质量情况及现行国家标准GB/T 494-1998《建筑石油沥青》的不足之处进行了分析。提出了今后应生产的建筑沥青品种及应参照美国材料与试验协会标准ASTM D312《屋顶用沥青的标准规格》、我国石化行业标准SH/T0002-1990(1998)《防水防潮石油沥青》,修订GB/T494- 1998的建议。以进一步达到增加建筑沥青牌号,提高建筑沥青质量和使用性能的目的,满足建筑工业的发展对沥青多牌号、高质量、使用性能好的要求。     

Performance and Commercial Application of the Promoter LCC-A for Maximization of Propylene Yield

1 Introduction Propylene as an important feedstock for organic chemicals is mainly originated from steam cracking and catalytic cracking processes. During the FCC process the propylene content varies with the FCC catalyst and process technology adopted, resulting in significant difference in propylene concentration in the cracked product——LPG. The conventional FCC pro- cess generally gives a propylene yield of around 4%, while the FCC process with maximization of propylene yield can in…     

加氢反应器制造技术的新进展

随着加氢装置的大型化,对加氢反应器的设计、主体材质的选用及制造均提出了新的、更高的要求。文章较全面地介绍了国内外加氢反应器的设计准则、主体材质(抗氢钢)和制造技术等方面的新进展。     

"适可而止"--"集合设计"在浙大网新科技园上的设计策略

“适可而止”是一种态度。文章用这个词归纳并品评了“集合设计”在浙大网新科技园项目上的设计策略。实际上,这种态度不仅体现在本项目的操作上,也反映在大部分中国建筑师目前时常面临的选择当中——关键是态度的指向能否逐渐形成更多积极性的策略。文章希望在追求“单纯性”、设计实验、细节控制和如何介入城市空间等方面的讨论能引导更多的读者有意识地用批判的眼光反观和印证自己的设计实践。