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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Iida M. Kuroda N. Otsuka H. Hirose M. Yamasaki Y. Ohta K. Shimakawa K. Nakabayashi T. Yamauchi H. Sano T. Gyohten T. Maruta M. Yamazaki A. Morishita F. Dosaka K. Takeuchi M. Arimoto K. 《Solid-State Circuits, IEEE Journal of》2005,40(11):2296-2304
A 16 Mb embedded DRAM macro in a fully CMOS logic compatible 90 nm process with a low noise core architecture and a high-accuracy post-fabrication tuning scheme has been developed. Based on the proposed techniques, 61% improvement of the sensing accuracy is realized. Even with the smallest 5 fF/cell capacitance, a 322 MHz random-cycle access while 32 ms data retention time which contributes to save the data retention power down to 60 /spl mu/W are achieved. 相似文献
982.
Christopher M. Gourlay Arne K. Dahle Hans I. Laukli 《Metallurgical and Materials Transactions A》2004,35(9):2881-2891
Banded defects are often found in high-pressure die castings. These bands can contain segregation, porosity, and/or tears,
and changing casting conditions and alloy are known to change the position and make-up of the bands. Due to the complex, dynamic
nature of the high-pressure die-casting (HPDC) process, it is very difficult to study the effect of individual parameters
on band formation. In the work presented here, bands of segregation similar to those found in cold-chamber HPDC aluminum alloys
were found in laboratory gravity die castings. Samples were cast with a range of fraction solids from 0 to 0.3 and the effect
of die temperature and external solid fraction on segregation bands was investigated. The results are considered with reference
to the rheological properties of the filling semisolid metal and a formation mechanism for bands is proposed by considering
flow past a solidifying immobile wall layer. 相似文献
983.
A new diffuser capable of scattering light in one direction (one-dimensional diffuser) has been developed and experimentally
tested. The diffuser is formed in a thick layer of dichromated gelatin. The scattering indicatrices of the diffuser measured
in two mutually perpendicular directions are presented. It is demonstrated that the indicatrix width in one direction is significantly
greater than that in the perpendicular direc-tion. However, no zero-order diffraction has been observed. The proposed one-dimensional
diffuser exhibits close scattering indicatrices for reading at a wavelength of 0.44 and 0.63 μm. 相似文献
984.
Grain refinement of Al-7Si alloys and the efficiency assessment by recognition of cooling curves 总被引:5,自引:0,他引:5
Under sand cup solidification condition, the influence of Ti, B concentration, and holding time on the grain size of a high-purity
Al-7Si alloy has been systematically studied. It is found that the grain size decreases rapidly at lower Ti or B additions,
and is almost constant at the higher concentrations. For Al-3B refined Al-7Si alloys, the grain size increases at the initial
period of holding time, and then rapidly becomes independent of holding time; while for Al-7Si alloys refined with Al-5Ti-1B,
the grain size increases with holding time throughout. To evaluate the refinement efficiency, a new method named “intelligent
evaluating of melt quality by pattern recognition of thermal analysis cooling curves” has also been introduced in this article.
The results show that comparing the cooling curve of the evaluated melt with those in a database to find the most similar
one to it can precisely assess the grain refinement efficiency of the measured Al-7Si alloy. In addition, the influence of
Ti, B addition levels, and pouring temperatures on some characteristic parameters of cooling curve has also been discussed. 相似文献
985.
A. Jaworek 《Journal of Materials Science》2007,42(1):266-297
Electrospraying utilises electrical forces for liquid atomisation. Droplets obtained by this method are highly charged to
a fraction of the Rayleigh limit. The advantage of electrospraying is that the droplets can be extremely small, down to the
order of 10’s nanometres, and the charge and size of the droplets can be controlled to some extent be electrical means. Motion
of the charged droplets can be controlled by electric field. The deposition efficiency of the charged spray on an object is
usually higher than that for uncharged droplets. Electrospray is, or potentially can be applied to many processes in industry
and in scientific instruments manufacturing. The paper reviews electrospray methods and devices, including liquid metal ion
sources, used for thin film deposition. This technique is applied in modern material technologies, microelectronics, micromachining,
and nanotechnology. 相似文献
986.
A method of measuring static and pulsed pressures using electrically conducting rubber sensors is proposed. The method is
based on a change in the volume resistivity of a filled rubber under the action of external pressure. The pressure-induced
change in resistance of the rubber sensor is proportional to the applied pressure and can be measured by a bridge circuit.
Using this method, it is possible to evaluate the degree of homogeneity of the pressure distribution over a solid surface.
This is achieved by distributing rubber sensors over the given surface. 相似文献
987.
988.
A fully-dense Cu-75 vol pct ZrW2O8 metal matrix composite was fabricated by hot isostatic pressing of Cu-coated ZrW2O8 particles. A small amount of the high-pressure γ-ZrW2O8 phase was created during the cooldown and depressurization following densification; near complete transformation to γ-ZrW2O8 was achieved by subsequent cold isostatic pressing. The thermal expansion behavior of the composite between 25°C and 325°C
was altered by the cold isostatic pressing treatment, and also depended on the length of time that had passed between thermal
cycles. The measured thermal expansion coefficients within specific temperature ranges varied from −6·10−6 K−1 to far above the thermal expansion coefficient of the copper matrix. The complex temperature-dependent expansion/contraction
behavior could be justified by considering the evolution of phase transformations taking place in the ZrW2O8 phase, which were observed by in-situ synchrotron X-ray diffraction measurements. 相似文献
989.
O. R. Dornyak 《Journal of Engineering Physics and Thermophysics》2003,76(3):648-654
A rheological equation of state for wood which allows for the running values of its porosity and humidity is considered. 相似文献
990.
S. O. Balanetskii B. Grushko K. Urban T. Ya. Velikanova 《Powder Metallurgy and Metal Ceramics》2004,43(9):480-483
Scanning and transmission electron microscopy have been combined with x-ray diffraction to examine the phase equilibria in the Al - Pd - Re system at 1000°C for compositions from 50 to 100 at.% Al, and the corresponding isothermal section has been constructed. The binary monoclinic Al3 Re phase has been observed for the first time. It is confirmed that there is a stable icosahedral phase in this system. The boundaries to its homogeneity region have been determined and the phase equilibria in which it participates. 相似文献