Differential competitive learning for centroid estimation and phoneme recognition.

A comparison is made of a differential-competitive-learning (DCL) system with two supervised competitive-learning (SCL) systems for centroid estimation and for phoneme recognition. DCL provides a form of unsupervised adaptive vector quantization. Standard stochastic competitive-learning systems learn only if neurons win a competition for activation induced by randomly sampled patterns. DCL systems learn only if the competing neurons change their competitive signal. Signal-velocity information provides unsupervised local reinforcement during learning. The sign of the neuronal signal derivative rewards winners and punishes losers. Standard competitive learning ignores instantaneous win-rate information. Synaptic fan-in vectors adaptively quantize the randomly sampled pattern space into nearest-neighbor decision classes. More generally, the synaptic-vector distribution estimates the unknown sampled probability density function p( x). Simulations showed that unsupervised DCL-trained synaptic vectors converged to class centroids at least as fast as, and wandered less about these centroids than, SCL-trained synaptic vectors did. Simulations on a small set of English phonemes favored DCL over SCL for classification accuracy.     

Chemistry and Physics of Alkali Metals on MoS2 Surfaces

The interaction of alkali metal with surfaces has been of great interest to the community of catalysis since alkali metal can play an important role as a promoter. On alkali-doped MoS₂, such a promotion effect of alkali metal has been exemplified in the direct synthesis of linear alcohols from CO and H₂, where the alkali-doping switches the catalyst selectivity from methanation to alcohol synthesis. This paper reviews recent high-resolution X-ray photoelectron spectroscopy experiments that have provided direct observation of electron transfer from alkali metals to a model single crystal MoS₂ and the capture of the supra-valence electrons in the subsequent oxidation reactions.     

RF-MBE生长的AlGaN/GaN高电子迁移率晶体管特性

用射频分子束外延技术研制出了室温迁移率为1035cm2/(V·s),二维电子气浓度为1.0×1013cm-2,77K迁移率为2653cm2/(V·s),二维电子气浓度为9.6×1012cm-2的AlGaN/GaN高电子迁移率晶体管材料.用此材料研制的器件(栅长为1μm,栅宽为80μm,源-漏间距为4μm)的室温非本征跨导为186mS/mm,最大漏极饱和电流密度为925mA/mm,特征频率为18.8GHz.     

在线近红外光谱分析仪在汽油自动调合系统中的应用

在线近红外光谱分析仪可以实时测定汽油调合组分及成品油的多种物化性质指标如烯烃、芳烃、苯及氧化物含量、辛烷值（RON、MON）、馏程、蒸气压等。文章介绍了用于汽油自动调舍工艺中的在线近红外光谱分析仪的原理、系统组成和特点，以及在国内外的汽油调合优化控制中的实际应用情况。典型的应用实例表明，将该分析仪用于汽油自动调合工艺中，可为炼油厂带来可观的经济效益和社会效益。     

具有复合埋层的新型SIMON材料的制备

采用氮氧共注入方法制备了新型的 SIMON(separation by implanted oxygen and nitrogen) SOI材料 .采用不同的制备方法分别制作出样品并进行了结构测试和分析 ,发现 SIMON材料的结构和质量对注入条件和退火工艺非常敏感 .并对各种氮氧复合注入技术做了分析和比较 ,发现氮氧分次注入可以得到更好的结构和性能     

涠洲11-4油藏聚合物驱聚合物性能评价及优选

针对涠洲11-4油藏温度和流体性质特征,通过收集国内外现有高性能抗盐和耐高温聚合物产品,对聚合物溶液的增粘性、稳定性、耐温性、抗盐性和抗剪切特性、阻力系数和残余阻力系数等进行了测试,并引入模糊综合评判方法,借以对不同品质聚合物溶液改善流度比或扩大波及体积能力做出全面和客观评价。实践证明,模糊综合评判是进行聚合物溶液优选的一种简洁和有效方法。通过对实验结果综合分析表明,在初选的几种聚合物中,“法国SNF”在综合评价中性能居优。     

Real-time palmprint acquisition system design

Capturing high quality palmprint images in a very short time period is a fundamental step in palmprint research. While a palmprint scanner capable of this function is especially important for developing a real-time online palmprint identification system, limited research effort has been put into designing and implementing palmprint acquisition systems. A novel palmprint acquisition system is presented, which is designed for various civilian applications such as access control, ATM, etc. The novel contactless design on the user interface prevents the distortion of the palm skin introduced by the traditional glass plate of a palm scanner. The system is designed to have the best performance at reasonable price. It has a resolution of 150 dpi that is able to obtain palmprint features, including the principal lines, wrinkles and ridge texture. The proposed system provides an important step for implementing a personal identification system using palmprint. Over 9,400 palmprint images were collected by the proposed system. An online palmprint identification system was then developed based on the proposed acquisition system.     

氨合成塔出口氨含量偏低原因分析及对策

阐述UHDE合成塔运行现状 ,分析氨净值达不到设计值的原因 ,提出相应的解决措施     

Speed–accuracy tradeoff in Fitts’ law tasks—on the equivalency of actual and nominal pointing precision

Pointing tasks in human–computer interaction obey certain speed–accuracy tradeoff rules. In general, the more accurate the task to be accomplished, the longer it takes and vice versa. Fitts’ law models the speed–accuracy tradeoff effect in pointing as imposed by the task parameters, through Fitts’ index of difficulty (I_d) based on the ratio of the nominal movement distance and the size of the target. Operating with different speed or accuracy biases, performers may utilize more or less area than the target specifies, introducing another subjective layer of speed–accuracy tradeoff relative to the task specification. A conventional approach to overcome the impact of the subjective layer of speed–accuracy tradeoff is to use the a posteriori “effective” pointing precision W_e in lieu of the nominal target width W. Such an approach has lacked a theoretical or empirical foundation. This study investigates the nature and the relationship of the two layers of speed–accuracy tradeoff by systematically controlling both I_d and the index of target utilization I_u in a set of four experiments. Their results show that the impacts of the two layers of speed–accuracy tradeoff are not fundamentally equivalent. The use of W_e could indeed compensate for the difference in target utilization, but not completely. More logical Fitts’ law parameter estimates can be obtained by the W_e adjustment, although its use also lowers the correlation between pointing time and the index of difficulty. The study also shows the complex interaction effect between I_d and I_u, suggesting that a simple and complete model accommodating both layers of speed–accuracy tradeoff may not exist.