基于加权类轴的Web文本分类方法研究

为了更有效的组织Intemet上丰富的信息资源，通过分析传统的近邻文本分类方法技术以及web文本的特点，提出了一种新的简单有效的网页分类方法。该方法充分利用了web文本的结构信息进行特征词加权，以类轴向量为核心构建分类器。实验表明，此方法具有较高的准确率和召回率。     

Quantum Computer Development with Single Ion Implantation

Spins of single donor atoms are attractive candidates for large scale quantum information processing in silicon. Formation of devices with a few qubits is crucial for validation of basic ideas and development of a scalable architecture. We describe our development of a single ion implantation technique for placement of single atoms into device structures. Collimated highly charged ion beams are aligned with a scanning probe microscope. Enhanced secondary electron emission due tohigh ion charge states (e.g., ³¹P¹³⁺, or ¹²⁶Te³³⁺)allows efficient detection of single ion impacts. Studies of electrical activation of low dose, low energy implants of ³¹P in silicon show a drastic effect of dopant segregation to the SiO₂/Si interface,while Si₃N₄/Si retards ³¹P segregation. We discuss resolution limiting factors in ion placement, and process challenges forintegration of single atom arrays with control gates and single electron transistors. PACS: 03.67.Lx, 34.50.Dy, 85.35.Gv, 73.23, 61.72, 86.40.py, 07.79.-v     

Dielectric Properties of B2O3 Doped MgTiO3-CaTiO3 System Ceramics

The dielectric ceramics with a main crystal phase of MGTiO3 and additional crystal phase of CaTiO3 were prepared by the conventional electronic ceramics technology .the strucures of MgTiO3 are ilmenitetype,and belong to hexagonal syngony.the ratio of MgTiO3 to Ca TiO3 doping on the dielectric properties of MGTiO3-CaTiO3(MCT)ceranics were inrestigated.the addition of B2O3 decreases the sintering temperatnre and results in rapid desification without obrious negative effect on the Q values of the system(Q=1/tan ).B2O3 exists as liquid phase in the sintering process,promoting the reactions as a singering agent.     

聚苯胺薄膜导电性的研究

采用樟脑磺酸作掺杂剂，对掺杂态聚苯胺薄膜的导电性能进行了研究。考察了掺杂剂用量、掺杂时间及温度对电导率的影响，并通过傅立叶红外吸收光谱(FTIR)和扫描电镜研究了PAn-CSA薄膜结构的变化。     

利用数据仓库技术支持商业信息系统中的品类管理

信息技术的发展促使了品类管理的快速发展。数据仓库是为适应决策支持系统的需要,在数据库的基础上发展起来的信息技术,具有广阔的应用前景。从建立品类管理信息系统的角度出发,通过分析其信息价值链的数据获取、数据管理、数据解析和决策支持这4个环节,描述了数据仓库技术在品类管理信息系统中的构建过程,并通过实例介绍了面向品类管理建立数据仓库的方法。     

Effect of Cd Doping on Structure and Superconductivity in Mg0.5Cd0.5B2

The effect of Cd doping on structure and superconductivity in Mg_0.5Cd_0.5B₂ fabricated by a solid-state reaction at ambient pressure has been investigated. The resulting changes in crystal structure, superconducting transition temperature T _c and critical current density J _c are characterized by X-ray diffraction, dc magnetization, electrical resistance, and magnetic measurements. It reveals that Cd does not occupy the atomic Mg sites in the MgB₂ crystal structure, but merely reacts with Mg and forms a MgCd₃ phase. It is striking to note that although the nonsuperconducting phase MgCd₃ is as high as about 67 vol.% in Mg_0.5Cd_0.5B₂, the T _c of the doped sample drops only by about 1 K. Most important, a surprising improvement of J _c of 5.0 × 10⁵ A/cm² (5 K, 0 T) has been achieved in Mg_0.5Cd_0.5B₂. It is suggested that the improvement in J _c in Mg_0.5Cd_0.5B₂ is primarily due to pinning effects induced by MgCd₃. Also, it is thought that MgCd₃ may fill up gaps among grains in MgB₂ and produce better grain linkage, which may be another source of improvement in J _c in Mg_0.5Cd_0.5B₂.     

Part-Set Cuing Effects in Younger and Older Adults.

In 3 experiments, the authors examined part-set cuing effects in younger and older adults. Participants heard lists of category exemplars and later recalled them. Recall was uncued or cued with a subset of studied items. In Experiment 1, participants were cued with some of the category names, and they remembered fewer never-cued categories than a free-recall condition. In Experiment 2, a similar effect was observed for category exemplar cues. There was also an age difference: By some measures, a small number of cues impaired older adults more than younger. Experiment 3 replicated this result and found that older adults were disproportionately slow in the presence of cues. Across experiments, older adults showed robust part-set cuing effects, and sometimes, they were disproportionately impaired by cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Category Learning in Rhesus Monkeys: A Study of the Shepard, Hovland, and Jenkins (1961) Tasks.

In influential research, R. N. Shepard, C. I. Hovland, and H. M. Jenkins (1961) surveyed humans' categorization abilities using tasks based in rules, exclusive-or (XOR) relations, and exemplar memorization. Humans' performance was poorly predicted by cue-conditioning or stimulus-generalization theories, causing Shepard et al. to describe it in terms of hypothesis selection and rule application that were possibly supported by verbal mediation. The authors of the current article surveyed monkeys' categorization abilities similarly. Monkeys, like humans, found category tasks with a single relevant dimension the easiest and perceptually chaotic tasks requiring exemplar memorization the most difficult. Monkeys, unlike humans, found tasks based in XOR relations very difficult. The authors discuss the character and basis of the species difference in categorization and consider whether monkeys are the generalization-based cognitive system that humans are not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schematic Influences on Category Learning and Recognition Memory.

The results from 3 category learning experiments suggest that items are better remembered when they violate a salient knowledge structure such as a rule. The more salient the knowledge structure, the stronger the memory for deviant items. The effect of learning errors on subsequent recognition appears to be mediated through the imposed knowledge structure. The recognition advantage for deviant items extends to unsupervised learning situations. Exemplar-based and hypothesis-testing models cannot account for these results. The authors propose a clustering account in which deviant items are better remembered because they are differentiated from clusters that capture regularities. The function of clusters is akin to that of schemas. Their results and analyses expose connections among research in category learning, schemas, stereotypes, and analogy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of A-site ionic size on the phase transition behavior of lead-free niobate ceramics

Understanding the phase structure evolution is important for developing high performance lead-free piezoelectric materials. In this work, the effects of A-site ionic size of monovalent ions on the phase transition behaviors for the lead-free niobate ceramics ANbO₃ (A = Li, Na, Ag, and K) are investigated using XRD analysis and dielectric measurement. The iso-valent ionic doping restrains the relaxation behavior that usually appears in the hetero-valent ionic-doped niobate ceramics. The A-site average ionic size of R_A and its ionic radius differences of ΔR_A are found to be crucial influence factors on the phase transition behaviors of the ANbO₃ ceramics. Small Li⁺ doping stabilize tetragonal phase of the ANbO₃ ceramics with R_A > 1.47 Å, but stabilize rhombohedral phase of the ones with R_A < 1.47 Å. On the other hand, The ANbO₃ ceramics without Li⁺ doping prefer to orthorhombic phase due to indistinctive ionic size differences (ΔR_A < 0.25 Å). Our results suggest that a certain phase and phase transition boundary could be designed by appropriate ionic doping for developing the niobate-based lead free piezoelectric ceramics.