“家”的隐喻与戏剧性呈现 四川德阳特殊教育学校设计的解读

德阳市特殊教育学校的设计以＂家＂的概念作为创作起点,建筑从儿童画里提取基本形态,形成纯粹几何体的组群聚落。文章在隐喻和戏剧性手法的叙事逻辑关联基础上,对设计作品中的原型提取、聚落层级关系、空间与界面操作等方面进行了深入分析。     

Structural and electrochromic properties of tungsten oxide prepared by surfactant-assisted process

By virtue of gemini surfactant template, nanostructured tungsten oxides thin films were prepared from the modified tungsten hexachloride sol-gel techniques. Temperature was varied as it is an important factor for crystallization, surface morphology and microstructure of tungsten oxides, from the studies of X-ray diffractions, scanning electron microscopy and transmission electron microscopy. The mesoporous sample calcined at 300 °C has tri-dimensional vermicular mesopores with nanocrystallites embedded in the pore wall, while such uniform structure would be destroyed by higher calcination temperature of about 400 °C. X-ray photoelectron spectroscopy was used for analyzing the surface-binding states and the stoichiometry for the oxides. Electrochromic characterization was implemented by simultaneous voltametric and spectrophotometric measurements of tungsten oxides/indium tin oxide (ITO) electrodes. The investigation results showed that organized pore-wall nanostructure has strong effects on the electrochemical and chromogenic properties depending on the specific surface area and the impacts from the evolved crystallization.     

Effect of heating mode on sintering of tungsten

Microwave heating is recognized for its various advantages, such as time and energy saving, very rapid heating rates, considerably reduced processing cycle time and temperature, fine microstructures and improved properties. The present paper investigates the feasibility of consolidating tungsten powders through microwave sintering. A comparative analysis has also been attempted between the sintering response of pure tungsten powder compact in a microwave and conventional furnace.     

Study of the mechanical properties of TiCN–WC–CO hardmetals by the interpretation of internal friction spectra

TiCN–WC–Mo–Co mixed carbide hardmetals have an interesting application potential for cutting tool fabrication combining the high toughness of WC–Co with the resistance to plastic deformation of TiCN–Co cermets. Mechanical spectroscopy (MS) is used in order to separate the effects of the constituents on the mechanical properties. Internal friction (IF) spectra are measured in a torsion pendulum on WC–TiCN–Mo–Co samples where TiCN/WC ratio is varied as well as the Co content. Six components of the characteristic IF spectrum of WC–TiCN–Mo–Co have been identified and interpreted. Two peaks are located in the cobalt, two peaks in the TiCN phase and two peaks in the ceramic grain boundaries. Four temperature domains are defined depending on the mechanical behaviour: brittle (I), anelastic (IIa), limited plasticity (IIb) and extended plasticity (III). The anelastic domain is characterized by the bulk deformation of cobalt. In the limited plasticity domain, both cobalt and TiCN are deformed by dislocation movement. The high temperature extended plasticity should be attributed to grain boundary sliding in the ceramic phase (mainly WC) enhanced by cobalt diffusion in the grain boundaries.     

碳化钨、钨及其复合物料中痕量砷的测定

对碳化钨样品中的痕量砷进行了分析测定,试样以硝酸、氢氟酸低温溶解,硫—磷混酸冒烟驱除硝酸和氢氟酸,用预还原剂还原高价砷(Ⅴ)为低价砷(Ⅲ),进行氢化物原子吸收光谱测定,测得结果与摄谱法及分光光度法结果一致。     

On a peculiarity of low-energy ion scattering from a well-ordered bcc W(2 1 1) surface

A peculiarity in the backscattering of keV He⁺ ions by a well-ordered high-purity W(2 1 1) surface is reported. Besides the normal elastic binary collision peak and the low-energy tail due to backscattering in deeper layers, an extra peak is observed for an inelastic loss of about 95 eV. This unusually large loss has a constant value over a wide range of primary energies (1.5-4.5 keV). An extra peculiarity is that the peak is only observed for the scattering in normal incidence towards the (2 1 1) plane. It is also not seen for polycrystalline W. The energy loss may be due to a quasi-double or -triple collisions of He particles with the row-trough structure of W(2 1 1) involving electronic excitation of both He and W atoms. Alternatively it may be due to a special channeling/dechanneling process for the incident ions.     

Evaporation of Pure Droplets in the Convective Regime Under High Mass Flux

An analytical expression analogous to the D² law was introduced, based on a mass transfer consideration, to describe the evaporation of pure droplets in the convective regime based on the Ranz-Marshall-type correlation for the Sh number. Comparison was made to single droplet drying experiments of pure water. It was found that the effect of mass transfer coefficient depression is significant under the high mass flux condition from the droplet. An expression was obtained to approximate the total time required for complete evaporation of a pure droplet. This expression can be used as a quick computation tool for more fundamental studies on droplet evaporation under controlled ambient conditions.     

Effects of low-frequency electromagnetic field on nucleation during the pure aluminium solidification process

The effects of low-frequency electromagnetic field (LFEF) on nucleation during the pure aluminium solidification process are investigated. The experimental results show that the primary structure cannot be refined by applying LFEF on high-temperature liquid phase. The LFEF can dissociate the nuclei from the mould wall and disperse them uniformly when The LFEF is applied during the nucleation stage. However, the temperature at the middle of mould is higher than the liquidus temperature of pure aluminium, and the crystal nuclei cannot be preserved and grow up.     

Oxide contributions on arc plasma in tungsten inert gas welding of magnesium alloy

Abstract

To study the effects of oxide activating flux on the arc plasma, the investigation is carried out in tungsten inert gas (TIG) welding on magnesium alloy. In this study, five oxides, ZnO, MnO₂, Cr₂O₃, CeO₂ and CdO, are selected to study the roles of activating flux on the plasma characteristics (shape, electron temperature and electron density) and the arc voltage. The mechanism is also discussed by comparisons between single TIG welding processes with and without fluxes. Results reveal that the electron temperature of arc plasma decreases sharply under the influence of oxide; however, the electron density and the arc voltage get enhanced. The reasons for the increase in arc voltage are the greater electricity resistances that result from the improved welding current density and the constriction of conduction channel.     

Deep drawing of tungsten plates for structural divertor applications in future fusion devices

The reference design of a helium cooled divertor for future fusion reactors makes use of hundreds of thousands of finger units consisting of a pressurized structural part called a thimble. Due to the high number of parts needed, the thimble has to be fabricated by mass production techniques like deep drawing. As the thimble is a pressurized part exposed to an internal pressure of 100 bar, the demands for the material are high, which means that it requires the best available tungsten material. Former work has shown that pure tungsten material has the best impact properties and has to be preferred over other commercially available tungsten materials, such as that doped with potassium or strengthened with oxides like lanthanum oxide.Furthermore the inherent weakness of the grain boundaries has to be taken into account, which requires the need for grains that are aligned to the contour of the part (grain boundary alignment).This paper describes the successful deep drawing of a 1 mm tungsten plate in high vacuum at 600 °C. In doing this, a thimble can be machined with grains that follow the contour. Furthermore the characterization of a 1 mm tungsten plate is conducted by tensile tests at room temperature and at 600 °C, as well as by Charpy tests taking into account the anisotropic material behaviour.