纳米铝晶粒生长的抑制方法(英文)

对纳米铝、铝合金和铝基化合物的晶粒生长行为进行了比较。首先,采用球磨粉末的烧结方法制备纳米铝。然后,添加能在晶界形成热稳定二次相和阻碍晶界运动的元素,如Mn、Zr和混合稀土元素,形成纳米铝合金。最后,因为多壁碳纳米管有望在晶界处抑制晶粒生长,因此,制备含有多壁碳纳米管的纳米铝复合材料。将3种样品在550 oC,5 d下进行退火处理,比较了退火时间对样品维氏硬度的影响。结果表明,采用多壁碳纳米管阻碍纳米铝晶粒生长的方法最为有效。     

CELLULAR STRUCTURE OF PEANUT-BASED EXTRUDED SNACK PRODUCTS USING SCANNING ELECTRON MICROSCOPY

A mixture of partially defatted peanut flour (12% fat) and rice flour was extruded to produce indirectly, puffed extrudates using a corotating twin-screw extruder. Extrudates were dried to obtain half-products of 11-12% moisture content, and the half-products were expanded by deep-fat frying. The effects of three levels of peanut flour (30, 40, and 50%), screw speed (200, 300, and 400 rpm) and feed rate (4, 5, and 6 kg/h) were studied by characterizing the cellular structure of expanded snack products using Scanning Electron Microscopy (SEM). Average cell size (mm²) and the number of cells per unit area (cm²) were determined from the interior cross-section area of snack products. Those parameters were influenced mainly by the level of peanut flour followed by screw speed and feed rate. Increasing peanut flour from 40 to 50% produced less puffed final products resulting in small cell size compared to snacks of 30 - 40% peanut flour. The maximum cell size was produced in the snack products extruded with peanut flour of 30 - 40% at screw speed of 250 - 330 rpm and feed rate of 4.7 - 5.7 kg/h. While the number of cells was relatively similar regardless of screw speed and feed rate, increasing peanut flour increased the number of cells. The cell walls became thicker with increasing feed rate.     

Nuclear symmetry energy from QCD sum rules

We calculated the nucleon self-energies in iso-spin asymmetric nuclear matter and obtained the nuclear symmetry energy by taking difference of these of neutron and proton. We find that the scalar （vector） self-energy part gives a negative （positive） contribution to the nuclear symmetry energy, consistent with the result from relativistic mean-field theories. Also, we found exact four-quark operator product expansion for nucleon sum rule. Among them, twist-4 matrix elements which can be extracted from deep inelastic scattering experiment constitute an essential part in the origin of the nuclear symmetry energy from QCD. Our result also extends early success of QCD sum rule in the symmetric nuclear matter to the asymmetric nuclear matter.     

AGING AND RELIABILITY OF PMN-PZT MULTILAYER CERAMIC ACTUATORS

ABSTRACT

Expected lifetime and reliability of multiplayer ceramic actuators were considered. 5 × 5 × 5 mm³ sized multilayer ceramic actuators with 60 ceramic sheet layers embedded internal electrodes were selected in this experimental analysis. Specially selected rectified AC bias was applied to the multilayer ceramic actuators to remove heating during charging and discharging process. 16 sets of multilayer ceramic actuators were tested for statistical analysis. Weibull function method was employed to calculate mean time to failure. Arrhenius model and power law model were considered to simulate experimental data. From the experimental data and theoretical consideration, equation of expected lifetime was estimated.     

Full Integration of Highly Reliable Phase Change Memory With Advanced Ring Type Bottom Electrode Contact

ABSTRACT

We successfully developed 256Mb Phase Change Random Access Memory (PRAM) based on 0.10μ m-CMOS technologies using ring type contact. The writing current with uniform CD process variation of Bottom Electrode Contact (BEC) was achieved by improving CMP process and developing core dielectric material. Also, the ring type contact scheme provided strong reliability such as the cycling endurance and data retention time for 256 Mb high density PRAM.     

Heating performance of a ground source heat pump system installed in a school building

The heating performance of a water-to-refrigerant type ground source heat pump system is represented in this paper under the actual working conditions of the GSHP(ground source heat pump) system during the winter season of 2008.Ten heat pump equipments with the capacity of 10 HP each and a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth were constructed.We investigated a variety of working conditions,including the outdoor temperature,the ground temperature,and the water tempe...     

The politics of public space planning in Singapore

This paper considers the role of, and hence the social and political significance that has been accorded to, the design and provision of public spaces in the urban planning process. This approach gives useful insights into understanding the role these spaces have played in the colonial and post‐colonial city of Singapore. This discussion argues that public spaces in both the colonial and the post‐colonial city are essentially constructions by the ruling élite and its planning regime and are thus politically charged. Popular involvement has been singularly lacking in the planning and development of public spaces in post‐colonial Singapore. Instead, the general public has been marginalized in the creation of these spaces by the colonial and post‐colonial state. The completeness of this exclusion is shown through the demise of most of the vital and liveliest, albeit previously appropriated, public spaces of the colonial city. Public housing and the re‐invention of public spaces provided by a new social and political order followed the end of British colonial rule. In the following discussion, the role and significance of public spaces through the colonial period and then in the post‐colonial developmental state are examined. It is shown that public space provision by government authorities has served initially more as an imposition of colonial ideals and social segregation, and latterly as a reification of the prevailing political ideology, than in meeting real public needs for such spaces. A major focus of this article is the use of public space as a political tool of control by the state over its denizens in the Foucauldian sense, and how this could be construed even through different systems of governance and political agendas in Singapore.     

Similarity measure design for high dimensional data

Information analysis of high dimensional data was carried out through similarity measure application. High dimensional data were considered as the a typical structure. Additionally, overlapped and non-overlapped data were introduced, and similarity measure analysis was also illustrated and compared with conventional similarity measure. As a result, overlapped data comparison was possible to present similarity with conventional similarity measure. Non-overlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considering high dimensional data analysis was designed with consideration of neighborhoods information. Conservative and strict solutions were proposed. Proposed similarity measure was applied to express financial fraud among multi dimensional datasets. In illustrative example, financial fraud similarity with respect to age, gender, qualification and job was presented. And with the proposed similarity measure, high dimensional personal data were calculated to evaluate how similar to the financial fraud. Calculation results show that the actual fraud has rather high similarity measure compared to the average, from minimal 0.0609 to maximal 0.1667.